my ipad wasnt connect to my computer it says usb device cannot recognize

See this to get the iPad recognized by the computer. If your computer doesn't recognize your iPhone, iPad, or iPod - Apple Support.

You can look at this for help with Restoring the iPad. If you can't update or restore your iPhone, iPad, or iPod touch - Apple Support

Quit iTunes (Mojave or earlier) or Finder (Catalina), disconnect the USB, reboot both the Mac and the iPad, re-connect the USB, re-launch iTunes (Mojave or earlier) or Finder (Catalina), and try again.

Failing that, disconnect all other USB devices other than a wired keyboard and mouse if you’re using one or both of those, disconnect and reboot it all again as above, and try again.