why does my computer always restarts

when booting,the screen turns blue and says that error in bios something like that,what should i do?plzz help me

Without knowing the exact error it is kind of hard to help you.

The best thing you can do is isolate the problem one by one. Possible problems could be:
corrupted files on operating system.
failing hard drive
motherboard problems: bios, add on cards, ram etc.

The first thing you have to do is to check your computers memory(ram).
You can do this by disabling the 'quick boot' option in the bios so that your computer will check the ram integrity when booting.
make the hard disk as the first hard drive and the CD ROM as the secondary drive.

if you have add-on cards, remove them and leave off only the basic configuration.

reinstall windows or better still format before reinstalling.