|Did you try using the repair? |
If you bought Windows 7 as a dvd then you may be able to boot to the dvd and use repair tools to fix it.
If you bought the dvd you may wish to simply reload the OS. This may cause your data to be lost.
If you had xp and you did an upgrade many other things may be lost and you should consider restoring it to xp first. Read the Owners Manual to see how. Then apply Windows 7.
"The era of big government is over," said Clinton 1996