Windows 10 issues after installing System Mechanic

You've already looked this up on google?

"System Mechanic" type software can cause problems and generally fix nothing.

Try running a system restore to a date before the changes were made and I suggest you dump the System Mechanic program.

That's weird

I rv wrote:
I installed Iolo System Mechanic one week ago. Whatever changes it made to my system, I can no longer access Windows Desktop so cannot access any tools or apps. to uninstall it. Help! Thanks in advance for any help.

You say you can "no longer access Windows Desktop" and gave no more info. Anyway, here is a link to seven ways to uninstall System Mechanic on Win 7,8,10. Caution... I do not recommend you download any software offered at that link! I can't vouch for it.

I use Iolo and have for years. The problem you present looks like what happens when installing Iolo on a system which already has an infection.
Call Iolo tech support, my past experience has been great with their help and advice.