Fix Black Screen at boot, continual restarts, or stuck at windows logo
This has worked for me in a number of cases where Windows will not boot. If the file system becomes corrupt from something like a virus issue this write a new boot sector to the system partition or repair the MBR.
First you will need to boot into windows Windows recovery console
If there is an administrator password you will need this, if not it can be cleared with an offline password recovery disk. (UBCD, or there are standalone ones as well)
Once the console is loaded you have to choose the installation you wish to repair.
At the prompt type “fixboot” to rewrite a new boot sector to the drive.
After this completes type “fixmbr” to repair the MBR this may be redundant but it doesnt hurt.
Finally you can also re-add the the installations of Windows to the boot.ini file by running the command “bootcfg /rebuild” this automatically scans the drive for installs and adds them to the file.
You can then reboot and see if this fixed your issue.
If you are still having problems or if recovery console does not see the installation run “chkdsk /r”, it never hurts.