,y computer is plugged in to power adapter but still says battery not charging

You don't provide enough specific details especially the exact model of the Mac which would allow us to provide more specific help. Here are two Apple articles regarding charging issues. Select the one which applies to your model laptop:

If your MagSafe cable or power adapter isn't working - Apple Support

If your USB-C power adapter isn't charging your Mac notebook - Apple Support

If this does not help, then have Apple or an Apple Authorized Service Provider examine the laptop and charger to provide you with a repair estimate.