Wipe the lens clean with a soft, dry cloth and take the photo again.
If new photos still look blurry:
You can try to recover recently deleted photos.
If recovered, make sure that you back up your photos to the cloud.
After each troubleshooting step, check to see if the issue has been fixed:
This error can occur if you use the camera in one app and then switch to another app that requires permission to access the camera.
After each troubleshooting step, check to see if the issue is fixed:
Check which apps have permission to access the camera.
Settings > Apps > App permissions > Camera
Review the list of the apps on your phone that request camera access and remove access for apps that look suspicious or that you don't use.
If you're getting messages about Deleted items being full: