I can't formate my PC

What error do you get? have you tryed a different disk?

yes,i tried.but,when i put the CD into drive,it doesnt want to boot,only windows start to work.i tried several timesand again and iagain,i entered into bios,and im sure all is fine,there

Does it give any error? or does it just restart? Anyway, its hard to tell just with what you said...
It can be anything... Does the computer boot normally? if it does it might even be the CD... if you can try to format on another SATA socket. Try formatting the HDD first on another computer, if you cant format it on another pc its most likely the HDD itself. If you can format it on another machine it can be something is wrong with the motherboard/memory...

You need to enter your BIOS and set it to boot first from cd/dvd.

there is no error,only the pc restarts,normally...and it seems like there is no CD into drive. and about whether i tryed or no,i tried with another cd,and im sure that it was bootable,cos the man who gave to me,recently formated his pc

yes,i did it,i set the Bios to boot first from cd/dvd

If it starts windows then the disk is not being read. Do you have anouther copy of your windows disk? you could try the ultimate boot disk as well.
http://www.ultimatebootcd.com/download.html
it may also be a bad DVD drive.

.................uh,i dint know what to think anymore,you are right,it could be anything..how ever ,thank you a lot,maybe im gona solve the problem,dont know,im such a biginner

i will try now to explain better,i put the cd into drive,than i restart the pc,than i got black screen with thesewords:to boot from cd/dvd and insted of start with formatting the pc, i only see that my windows 7 stars with work and everything works like there is no cd into cd drive

If you are seeing a black screen with the words "to boot from this cd/dvd" you should be hitting the enter key within 3 seconds.

hello,u suggested to me to try with:http://www.ultimatebootcd.com/download.htlm, i downloaded and put it on cd,what next should i do? thamks

...............................few days passed,already,and i did ,finaly,thank you a lot

Best answer selected by malaquecue.

I think i have the same problem... what happens with my computer is that i put the windows 7 dvd and restart my computer (my computer boots the DVD/CD drive first as it should). i get the black screen that i am supposed to get BUT nothing comes up, the screen stays black for a while, as if the computer is trying to read the dvd then after about 5-10 secs the computer starts normally. i know i am doing everything right because i format-ed my computer before but obviously there is something wrong with the computer......... any ways to solve this or any other way to format a computer