My iPhone 11 will no longer take a screenshot when I press the volume and side button. Any suggestions?

Have you tried any troubleshooting? There are no support documents with troubleshooting steps. General user troubleshooting for the iPhone include in order, power the iPhone off and back on, if needed, then reset the iPhone (Force restart iPhone - Apple Support), then if needed restore from a backup, Restore your iPhone, iPad, or iPod touch from a backup - Apple Support and if needed restore to factory and set up as new. Restore your iPhone, iPad, or iPod to factory settings - Apple Support

Making sure that you are using the Volume Up and side power button together to take the screenshot? What troubleshooting have you tried? Do you have ample storage for photos?