you can try this from a command line window while the Feathercoin-gui is open:
feathercoin-cli rescanblockchain
Alternatively state ‘rescanblockchain’ in the console window of the feathercoin-gui
This forces to scan the full blockchain again and get the transactions corresponding to your addresses.
By the way, if you check the ‘receiving addresses’ list, are your ‘old’ addresses are shown?