You may encounter some issues on your iPhone that cannot be resolved, so you can try resetting all or part of the iPhone to see if it resolves the problem.
Before resetting your device, back up important information and transfer them to a computer or backup with iCloud keychain, then go to Settings, select Reset, and choose Reset All Settings.
Instead of resetting all the settings on your iPhone, I recommend resetting part of the settings on your iPhone.
Step 1. Go to Settings>General>Reset.
Step 2. Find Reset Network Settings in the middle of the screen.
Step 3. Tap the option and input your password.
Resetting iPhone network settings can help clear the network settings quickly, allowing you to start fresh.
If your iPhone GPS is not working, try resetting the location and privacy settings to resolve the issue.
Step 1. Go to Settings>General>Reset.
Step 2. Find Reset Location and Privacy option at the bottom.
Step 3. Tap the option and input your password.
Step 4. Open the Map and Compass on your iPhone to check if it's helpful after reset iPhone privacy and location.
This part is more powerful than the first part as it not only resets iPhone settings but also clears information. If you want to wipe this iPhone and restore from another already activated iPhone.
Step 1. Go to Settings>General>Reset.
Step 2. Find Reset Erase All Content and Settings option on the top.
Step 3. Tap the option and input your password.
Now that you've erased your iPhone, the next step is to restore it. You can choose to restore it from iTunes or directly restore it to its factory settings.
Step 1. Open iTunes on the computer.
Step 2. Make sure your iPhone is well-connected to your computer.
Step 3. Click on the icon of your iPhone.
Step 4. Click on "Restore Backup".
Step 5. Select one of these backups, and click "Restore" to start this process.