Bitcoin QT wallet crashed. Recovered using Bitcoin Core. Now password rejected!
As far as I know the versions should be backward compatible but I don't know how far back, 5 years is quite a long time, Bitcoin Core have had 30 releases since then.

I found two changes that might impact wallet compatibility in my opinion:

Version 0.9.0 (19 March 2014):


  Also, the first time you run a 0.8.x release on a 0.9 wallet it will
  rescan the blockchain for missing spent coins, which will take a long
  time (tens of minutes on a typical machine).


Version 0.13.0 (23 August 2016):


  HD wallets are incompatible with older versions of Bitcoin Core.


Anyways, I would suggest to make a backup copy of your wallet, download an older version of Bitcoin Core, copy the wallet to the data directory of that client (you might need to specify it using -datadir C:\bitcoin_old\data), start the client (no need to synchronize the blockchain), export the private keys, exit, move away the wallet.dat from the data dir of your new Bitcoin Core client, then start it and import the private keys to your newly created wallet.