Shell.dll errors are caused by situations that lead to the removal or corruption of the shell DLL file.

Follow these steps in the order they are listed below to try the simpler solutions first.

Recover shell.dll from the Recycle Bin. The simplest possible cause of a "missing" shell.dll file is that you accidentally deleted it.

If you suspect this, but you've already emptied the Recycle Bin, you may be able to recover the file with a free data recovery program.