To restore your PandaBank from a backup file (Either a copy of wallet.dat or a backup file you created) Close the PandaBank program.
Open File Explorer, for windows you can press the windows key + r then in the run entry type %appdata%\Pandacoin
then press enter. for windows the folder should be something like this C:\Users\%username%\AppData\Roaming\Pandacoin
You should backup whats there so Right click wallet.dat file and select Rename – edit the filename to be oldwallet.dat
Copy your backup file to the C:\Users\%username%\AppData\Roaming\Pandacoin folder. Rename the backup file to be wallet.dat by right clicking the file and selecting Rename if it is not already.
Close file explorer and then Open your PandaBank and wait for it to complete synchronizing.