My computer won't turn off? Please help!?

Ok till yesterday my computer worked fine but when i turned it off last night it restarted.As it never happened before i ignored it and in hurry i pulled out the main power cable.Today when i turned it on to copy some files and then turned it off it restarted again and then i got curious and intentionally turned it off several times but the problem remained there i also tried to restore it to previous date but it said"System Restore could not complete due to improper shut down".Please help me here?