I cant log in the

well it culd be a boot issue

for starting ur computer

press ctrl+alt+del

go to task manager

click on new task

enter explorer.exe ther and hit enter

c if the computer comes on this way

Wyhen you power up the computer press F8 key then enter in safe mode.
Then go to start menu ->run type in run "chkdsk /r"
then press "y"
then restart computer then it fix error on harddisk.Also scan your computer with antivirus in safe mode.
Remove all temp files from computer.
Let me know if you need further assistance.
Thanks.