Can't access dashboard plus blog theme is gone

Change the urls back. See Changing_The_Site_URL for details of how to do this correctly without logging in.

I can’t access the dashboard.

See Changing_The_Site_URL for details of how to do this correctly without logging in.

Thank you. I didn’t understand at first.

OK, now I can access the dashboard. I can also see the front page of my blog.

BUT, none of the pages of my blog work. I still get this error:
No input file specified.

Try resetting your custom permalinks back to the default setting via Settings -> Permalinks. If this works, then review Using_Permalinks before setting a custom permalink structure back up again.

OMG you’re brilliant!!! Thank you, thank you, thank you! ?? ?? ??

Glad I could help ??

Me too. You rock!