It's conceivable that the Wi-Fi network you're using has become corrupted and is no longer functioning properly. Turning Wi-Fi on and off is a common initial step in resolving such issues. If it doesn't work, you might try forgetting or deleting your Wi-Fi network. This means you'll have to rejoin after resetting your Wi-Fi network. Here's how to go about it:

1. Go to the Settings tab.
2. If necessary, tap to switch on Wi-Fi.
3. In the list, find and pick your Wi-Fi network.
4. Next to your Wi-Fi network, tap the blue I or information symbol.
5. Choose to Forget this Network from the drop-down menu. Your wireless network will be erased from the phone's memory if you do so.
6. To continue, enter your device passcode if requested.
7. Then press to accept the Wi-Fi network deletion option.
8. When the network has been successfully erased, restart your iPhone.
9. Return to the Wi-Fi option in Settings and scan for accessible wireless networks. Tap the Join option after selecting your Wi-Fi network.