The error happens because you use pruned mode, but want to load wallet.dat which never loaded previously or loaded after long time.
You can follow the Bitcoin Core suggestion (where you must download whole blockchain again) or simply extract the private key and load it to SPV wallet (such as Electrum).

But if you don't use pruned mode, please find debug.log (which located on folder where you store blockchain files & wallet.dat) and share it with us.