Thank you all - it seems my choices are pay for either EaseUS or Stellar as they start the process and obviously get past the lost partition. I am not sure how much of my USB would be recoverable and pay about $100.
or
format the disk and see if Recuva can recover the deleted files - but there is a limit of ?? (MB) - how many MB Recuva will recover for free?
I see - I have used EaseUS and Stellar - thy are ableto get to thefiles on the USB. However it is very expensive to use either one of those, especially as it is a once-off and I don't think I need the year's subscription