Problem with recording sample rates

Urgent help needed please!
I recorded a long VO job using 24-bit 48kHz, as this was the specified format. (I would normally use 16-bit, 44Hz). I didn’t save it as an Audacity project, just exported it as a wav file for editing later. However when I try to play the file now, I sound like a chipmunk - squeaky and speeded up - and when I try to change tempo to slow it down, it just further distorts the sound. Is there ANY way I can undo the chipmunk distortion and revert to my original recording quality/sample rate??? All advice gratefully received!
Thank you :slight_smile:

Just to clarify - I’m using Mac OSMojave 10.14 and Audacity 2.4.1
Also the following: Rode NT1-A, Steinberg UR22MkII
Thank you in advance for any advice, I’m tearing my hair out trying to record in the required spec of 24bit, 48kHz without sounding like a chipmunk!

change speed?