why is my printer unable to scan to my computer

What printer are you using?

What Mac model and year?

Which macOS version?

So that we can help you best, please tell us which Mac, model and year you’re having trouble with, and what macOS version you’re running. Find that info by clicking the  (Apple) menu at the top-left of your screen and then select About This Mac.

(Note- for privacy and security please don’t post your serial number.)

Meanwhile, it sounds like you need to reinstall your printer and/or printer drivers.

Please see: Add a printer to your printer list so you can use it on Mac - Apple Support

What printer are you using?

What Mac model and year?

Which macOS version?

Has your printer ever worked with that Mac?

When did it stop working?

Please see: Reset the printing system on your Mac to solve a problem - Apple Support

ALso: Scan images in Image Capture on Mac - Apple Support