Hi there, I am a complete starcraft 2 noob, but so far have been doing ok. I have won 4 out of 6 matches on 1v1. However the two matches I lost were both against terran players who seem to absolutely own me.
I play protoss, and generally try some kind of zealot and stalkers tactic but always get owned. 
For example I was building up a massive force of zealots, stalkers and dark templar ready for an attack, then out of nowhere a nuke landed and wiped outmy entire army! Needless to say I lost shortly after.
 Any advice against the terrans?

Protoss seem to whoop my ass as a terran player if i let them tech up and get higher tier units. I usually try to deal with them quick or annoy them a lot. 
 
Best bet from someone who admittedly isn't an expert on this game is to try and keep the guy pinned in his own base and tech up yourself. Keep an eye out for expansions and deal with them.

Try to keep pressure up on his base so he goes on the defensive, that gives you a chance to mass up you forces and tech up. And scout, always scout to figure out what you need to counter.

The problem is that u're a little too inexperienced to give concrete advice because there are just too many contingencies in the games u play, that we can't give u proper advice. We could give u advice if u would always lose vs the same strategy. In you're situatin u should just try to play many more games. Get like 100 games done to familiarize urself better with the game, best play some matches with all races. Doens't matter too much if u lose. 
In you're example u lost because u didnt have detection for invisibility. U should always have some kind of detection if u are unsure if the opponent can have invisible units.  
I would say the most important thing is to play alot though. U could also pick one build order u find on a site like team liquid and try to practice it over and over. But i think if u really want to learn the game its important to get out of your comfort zone as often as possible and don't learn one type of cheesy start and play only that (which can easily get u in gold). 
Another thing besides getting familiarty is trying to always keep building drones and always keep ur money low. Those are like 2 of the major factors that lead to winning. If u get a strong economy it will also get into gold league in no time. 

Rush early with 4 zealots asap to pressure their base, try to get a robotics facility asap and produce observers. ALWAYS scout the opponents base, this way you can counter what they're producing.  The Warp in ability is also really helpful for protoss, once you start learning it build up to 3-4 warp gates and convert them over, every 10 seconds you'll be able to warp in units.
 
If the Terran are looking like massing marines, marauders build a few High Templars with psionic storm. You've got to manually cast it but it'll wreck groups of biological units. 

" @JimmyTheExploder: My advice in that particular situation would be to try some ealier attacks to prevent the Terran player from getting a nuke. Also you should probably be producing observers from your robotics facility. You can use them for scouting out the terran base and would have seen his ghost academy (the building that allows him to make ghosts and holds nukes) and they are also able to detect cloaked units. When a ghost is calling down a nuclear missile he has to sit stationary for about 15 seconds so if you can spot him with an observer and take him out you can avoid the nuke entirely. Another option is to just move your army since he's either going to be nuking your army or your nexus to try wipe out your probes.  My biggest piece of advice since you say you're a new player would be to learn the tech tree of all 3 races even though you are only playing Protoss. You have to know what they can do before you can beat them. "

Thanks guys some great advice here!

It would also be pretty helpful to watch some more experienced Protoss matches. 
Or if you think you have a good handle on Terran (shouldn't be too hard if you've played through the campaign), you could try playing as Terran vs Protoss. As Terran you can use those strategies that were used to beat you against other Protoss players to see how they react.

Hi guys quick update, im still getting owned down by terrans, yet im beating every other race hands down!!
Could anybody be so kind to have a quick glance at a replay and give me some pointers?
 
Ive uploaded it to here: 
http://www.megaupload.com/?d=ZOP7F02J
 
anyway help would be appreciated :)
 

Make sure you have some observers. Also have some sentries to use guardian shield. It reduces some of the damage. Also get some immortals on your army and eventually some Collusi too.

I am in the opposite situation. I cannot, for the life of me, beat protoss (as terran), even though i make sure to make some early marauders, they get me with early Zealot rush. 
 
I guess that is an advice worth giving: Remember to put some early pressure on the terran player, even if you only have 4 zealots, you can do some serious dirt to your opponent.
 
You can also watch some commentary on some PvT matches, i strongly recommend checking out Day9's videos at:
  http://day9tv.blip.tv/ 
 

Always go for the supply lines when you can....maybe that's too obvious.

" I am in the opposite situation. I cannot, for the life of me, beat protoss (as terran), even though i make sure to make some early marauders, they get me with early Zealot rush. 
 
I guess that is an advice worth giving: Remember to put some early pressure on the terran player, even if you only have 4 zealots, you can do some serious dirt to your opponent.
 
You can also watch some commentary on some PvT matches, i strongly recommend checking out Day9's videos at:
  http://day9tv.blip.tv/ 
 

EDIT: And remember to tech up, void rays can be devastating if they haven't been scouted.

"