Why is my finger print dosn't work

@yusufridwan first you need to make sure that it is enabled in the settings menu. Go to Biometric, then Fingerprints and setup your prints. If the reader is not even being seen, then it is possible that you have a failed reader. Of course, you can also try to start your phone in safe mode and see if that changed anything. That would rule out that 3rd part software messes with your sensor. To enter safe mode :

1. hold the power key until the Power off icon appears.
2. Press and hold the Power off icon until the Safe Mode prompt appears.
3. Select Safe Mode to confirm.

You could also try a factory reset. Just make sure that you have backed up all of your files and that you know/have all of your passwords and access codes.

Now, if that does not repair your fingerprint reader, you will have to do a deeper check. Here is the Samsung flowchart for the Fingerprint Sensor not working

Uses this document Samsung S20 Component Layout and with the search function of your PDF reader, find the proper components as required from the flowchart.

Since iFixit does not yet have a guide for this, use something like this guide to replace it. A new sensor flex is readily available at many online stores. Use a vendor that appeals to you.

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.