Question / Help Loses audio and won't open

[KOS]

HI guys, I've been struggling with OBS. I have a live show to stream tonight but not looking like I can trust it at the moment. I've created two scenes. One for an Intro/out before and after the show and then a twin camera show with added audio. The problems I'm having are (sometimes) when jumping between the scenes or going elsewhere to do something on the PC when I come back to OBS it has lost the audio from the desk. I then "hide in mixer" show in mixer and the audio is back but I can't here it unless i shut down OBS and restart it. Also when trying to open obs It won't start and says "OBS is already running". so I go the task manager and end process of the OBS that's there. Sometimes this works but others it doesn't and I have to shut the PC. If i try running as admin it still does the same. and if i try to launch anyway it does nothing. Help would be very much appreciated.