Sounds like your iPhone is stuck in recovery mode. This usually happens if your update didnt finish properly. Here’s some troubleshooting methods:
If you’re accessing iTunes through Windows, make sure iTunes is using the latest version and feel free to update it on the Microsoft Store if not. If you’re using macOS Catalina or later, you’re gonna wanna use Finder instead.
Plug your iPhone into the computer and open iTunes/Finder (depending on what OS you’re using). When you see the “there’s a problem” message, choose Update first. Don’t worry, you won’t lose your data. If Update fails, choose Restore and select an iCloud backup. If none are present, your phone will be erased sadly.
If iTunes or Finder doesn’t detect it, try using another USB cable or another USB port if you can confirm one of the two is working. Preferably a USB port that plugs directly into the desktop, rather than a hub or docking station. If that fails, try another computer.
If you’re still stuck, you might need DFU mode. Connect to the computer and quickly press Volume Up, Volume Down, then hold side Button until the screen goes black. Ones it does, hold Side Button + Volume Down together for 5 seconds, then release Side Button but keep holding Volume Down for another 5ish seconds. The screen will stay black, but iTunes or FInder should now detect “a device in recovery mode”. From there, click Restore.
Hope this helps! If all else fails, I’ll try to diagnose the problem further and seek further ways of restoration.