Loudspeaker sometimes works sometimes doesn't

@overflowunt “if I beat the phone on the back a few times, the sound comes back to normal, “ sounds like a bad connection or a bad speaker. It’ll all be a guess until you open it up and see what damage awaits you. Once you do that, post some good pictures of your logic board etc., with your QUESTION. That way we can see what you see. Adding images to an existing question

While you are add it, go ahead and repair the broken screen since the speaker is mounted to it. It is not a complicated task just follow this guide iPhone 5s Earpiece Speaker Replacement. It’ll eliminate some of the guessing as well.

@overflowunt yes there is since the bottom speaker is attached to the back of the case. Principal still applies. Open it up, repair the front assembly, check the ribbon cables, connectors and worst case replace the speaker iPhone 5s Speaker Replacement