Printer won't connect
Printers lose touch with computers all the time, and a few restarts plus a fresh setup usually gets them talking again.
Be careful: Only get printer software from the printer maker's own website or the official app store. Ads offering 'printer help' or asking you to call a number are often scams.
What to do
Step 1: Turn the printer off, wait 30 seconds, and turn it back on. Make sure it shows no error lights or messages.
Step 2: Restart the Mac.
Step 3: If the printer uses Wi-Fi, check on the printer's screen or lights that it's connected, and that it's on the same Wi-Fi network as your Mac.
Step 4: If it uses a cable, unplug it at both ends and plug it back in.
Step 5: If it still won't print, restart your Wi-Fi router: unplug it, wait 30 seconds, plug it back in, then wait a few minutes.
Step 6: Open the Apple menu, click System Settings, then Printers & Scanners. Click your printer, then click Remove Printer (on some versions you right-click or Control-click the printer to find it).
Step 7: Click Add Printer, Scanner, or Fax, pick your printer from the list, and click Add.
Step 8: If it doesn't appear, install the printer maker's official app from the App Store or the maker's own website.
Still stuck? If the printer can't join Wi-Fi at all, use its own setup screen or the maker's official app, or contact the printer maker's support.