iPad sound not working after iOS 8

I updated my iPad 2 to iOS 8.3 the other day and the sound has been working fine up until today. I've tried restarting it a number of times and nothing works. The volume buttons don't work at all unless I have headphones in; using headphones is the only time I get sound. The sound randomly started working again about 5 minutes ago after I punched the iPad a few times out of frustration, but now it's just stopped again.

I know a few others have had this issue with the new update, but does anyone know how to fix it?