I suspect you went here:
HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
If so,and you are in dire straits - no backup,etc, there are a couple of desperate measures you could try.
First, open "programs and features" in the Control Panel. Up on the left, click "Turn Windows Features on or off"
Scroll down and untick IE(x -Whatever version you have) Ok it and wait until the action is complete.Reboot and, if the OS does not start the sequence automatically, repeat the above procedure and tick the IE item. Ok again and reboot. See if this has sorted the problem.
If not, here is a reg file which will return IE registry to its original settings.First export your registry to a known location, so that you can recover it back to the original. Open the attached .zip and click the unzipped file, agree to the warnings. No guarantees, so at you risk. But if your OS has developed serious faults, then maybe worth a try.
Note. This is only going to have any effect, if it was the entry above that you tampered with.