Possible File Association Problem or Open With Problem! MAJOR

Apologies if this is not the appropriate catagory but i had trouble finding a suitable one, here is my problem:

I was messing about with a file using winrar, (sorry i cant remember which file it was) i right clicked the file and clicked 'open with' i chose winRAR and it screwed up and decided every single program on my computer could only be opened by winRAR, (every icon was changed to the winRAR icon etc.) then in my frustration i deleted winrar hoping it would then sort itself out, it didnt. (i realise this was stupid now) i then restarted my pc to find things worse, the dock at the top of my screen could no longer start up along with numurous other programmes. somehow i managed to change it from winRAR to itunes, and then every time i opened a file it opened itunes instead, ideal if i wanted itunes and only itunes, but i dont -_- i then found i can access all the programs via finding them directly (my computer, etc.)so i managed to open the internet and type this for example, i searched google i found several problems just like mine, however none of the solutions worked. i then changed it to adobe reader, again every program opened adobe reader, and then to some internet explorer thing, i have no idea what has happened.

Basically i need to set every programme to its default startup file thing (if that makes any sense at all) if you need more information as to what ive done then feel free to ask, any help is welcome!

Please Help,
Russell.

P.S. The Attached file is a .png of my computer, notice no dell dock at the top, the three programs at the bottom left are all using the same icon for what ever programme its changed to now, (the programmes should be like this from left to right: Internet Explorer, Hamachi, Norton 360 (The one with the green tick)) Also notice the open start menu, with all the programmes using the same icon, all opening the same thing, despite what they should open. like i said i have full acces to everything on my computer via my computer and navigating to them, so why dont these work? (the programmes at the bottom were opened via my computer etc.) Excuse the background.

Thanks in advance.

Thankyou for your time danny and Milesahead, unfortuneately i dont have a restore point though.

As for you danny i tried te first option you gave me and tried the .exe (To be fair i dont know much about computers) and i didnt work, i was wandering if you (or anyone) happened to know what type programs like Internet explorer, Norton 360, iTunes and Microsoft office Word etc. are so i can fix those as they are a priority.
As for your second option, i had already tried that and it refused to work, infact i beleive that was what caused the problem...... (i did that or similar and it set every programmes default to the same programme if you understand)

Thanks again Danny and Milesahead, i apreciate the help! (And anyone else in advance)

Russell.

Oh okay so i did use the right one, and yes i did reboot. Yes that does work opening from their default locations) which luckily has allowed me to write this, and use other programmes to ask friends for help. However this is inconveniant and would be much easier if my dell dock and start menu worked.

hmm setting the default programs dosent seem to of done much either.

Okay i have just dont the .lnk and .exe, and i am rebooting now.

Hopefully this works, Ill let you know in a few minutes.

Thanks again, i really appreciate it.

Russell.

SOrry boobah i didnt see your comment while i was writing my reply, thanks anyway but...

IT WORKED!

Thankyou so much for your time guys, especially danny!