Hello, really hoping someone will now the answer to this! I record a news bulletin from home every week and until last week the recording was perfectly good. However when I came to record last Monday I played back too slowly. I haven’t changed anything. I’ve tried re-downloading Audacity but that didn’t help. What could be the cause? Soundcard in my laptop? I record using a Presonsus USB interface and a Rode NT1 mic. Please help before I chuck the whole out of the window 
It’s probably due to mismatched sample rates. If so, then we should be able to correct it.
What were you playing back, the Audacity project, or an exported audio file?