Before you do anything that you think of or that may be suggested... First make certain you have your contacts already backed up.
If they are being saved to your Google account... Log onto your account with a standard computer and go to the Google Contacts to ensure they are all there. If they exist there... that should work as a backup... if not or you wish to make doubly certain you are safe from loosing your contacts...
Open the Contact app you are using and export your contacts to a file. Then copy that file to a computer or onto your Google drive ( if you have an account of course ) or somewhere in the cloud that you can get to later if needed to restore.
Once you are certain you have a backup plan... then reset the Contact app and clear it's cache. If your contacts are in your Google account... resync your account and it should repopulate your Contact app. If your contacts were not in your Google account, import them from the backup you made earlier.
If you use a different contact app than the default, the instructions should still be similar but may have minor differences.