Update your post to include full hardware specs.
Did you back up the Registry as recommended before doing the edits?
If so, restore via the backup.
If not, did you keep any notes regarding what you changed, where you changed it, and what you changed it from/ to?
Registry editing is a last resort and should only be used if the requirement is clear and is fully documented. And after, as always, making backups then verifying that the backups are recoverable and readable.
What specific things were you trying to tweak?
Maybe reinstall the GPU drivers....