I have several files in two cryptometer vaults on my iMac which I have been accessing regularly. Today when I opened crypto meter the two vaults with files are gone
Do you mean the vaults are not listed in the app anymore, or are file files in the vault missing?
If just the vaults are not listed anymore, you can just add them again.
https://docs.cryptomator.org/en/latest/android/vault-management/#add-existing-vaults