remove trojan help!! - cant access anything!

[Aurannette]

i have a trojan ( i think it is, at least. a friend told me it was) that won't let me access anything! my SBC browser has been blocked, i cant access any of my anti-spyware programs, anti-malware, etc. Sims 3 doesnt even work!!! I tried doing an online scan, and that just shut me out and locked me out of my browser. iexplorer doesnt work, b/c that;s taken over by the trojan. I get pop-ups here and there, not all at once, but maybe like 1 every 2 min. or so. (ive had worse). diagnostic start-up doesnt work. Oh, also, I CAN NOT ACCESS ANY SAFE MODE SETTING. I did access the "restore windows to the last known setting it worked" or w/e its called. but i still get access denied. pop-ups tend to be search engines. when i tried to access safe mode, it would just restart my computer.

Please help! this is the worst thing ever to happen to me on my computer, and for me in general b/c i cannot lose everything on this computer. I have so much on here that i need.

THanks in advance, every bit of info is crucially appreciated!! thanks again!!

[giedmaja]

Step 1. would be backup all the data you got into CD/DVDs or flash drives. Preferably DVDs.
Do not backup programs, only documents and other data.
Step 2. We need to identify what threats are on your PC. I would recommend either hijackthis or couple good anti-spyware/Antivirus programs. Typically, Hijackthis is not blocked by malicious applications (although it does not check all the points in modern systems).
Post the results in forums and we will see how you can get help.
If you can not download these programs directly, I would recommend downloading them to flash drive (or, even better, CD)  on other PC.
As antivirus programs I strongly recommend ESET's NOD32 (free trial available at http://www.2-viruses.com/eset-nod32-antivirus ). AVG is ok too, although it has no rootkit detection at the moment. Avira, avast are an option as well.
As anti-spyware I recommend spyware doctor (free scanner). Malwarebytes anti-malware are ok, but they scan results are often generic names of parasites, so it is hard to guess what parasites there might be left.