I could not able to login in computer

Hello,

When I turn on the computer, I can get the start page, then I get the page with Press F2, then it shows the options safe mode, with command prompt, last good known... etc, But I could not able to any one of them. When I select any one from those options, It comes to the start page and Press F2 and the Safe mode option page again, Please give any solution for this issue.

Thankyou.