How can I manually add a receiving address in MultiBit Classic Wallet - disconnected during confirmation
You may have the receiving address in one of the rolling backups.
Also, if your wallet is encrypted then when you create a new receiving address then an export of all the private keys is performed automatically (encrypted with the wallet password).

Where all the files are stored is described in:
https://multibit.org/en/help/v0.5/help_fileDescriptions.html