iMac will not connect to mouse and keyboard

You need to get and use a USB keyboard and mouse to help get then reconnected. FWIW most any USB generic or pc keyboard and mouse will work with your Mac.

If your devices are not pairing or bluetooth is turned off, then you need to use a USB keyboard and mouse to help get then reconnected. FWIW most any USB generic or pc keyboard and mouse will work with Mac's.

also see > If your Apple wireless mouse, keyboard, or trackpad isn't working with your Mac as expected - Apple Support

Mac will not connect to mouse and keyboard I can’t get into my Mac