Depending on if you have things like photos or other personal information that is not backed up already, you should be able to do a factory reset on your phone, it will completely reset all off your device and wipe any personal information but may resolve the issue.
The other option is known as a soft reset, this might be possible and you wouldn't lose personal data, however it depends on what phone you have as to which option would be available.
Both these option rule out if it's the phones software causing the issue or if it's a hardware issue (eg the speakers damaged by water)
