Sorry I missed your replies until now.
I'll go ahead and try your ideas.
I did get an error message after reinstalling windows and litcoin-core wallet - so at least one of the backups seems to be corrupted.
I originally installed litecoin-core on April 8th, made the small purchase on the 9th, then, during the 9th i formated and reinstalled win10, and then made the bigger purchase on April 10th.

Edit: I just found in my backup folder a file named litecoin-wallet-keys-2017-04-09-011837.dat
Could this be of any help?

No luck...
It's practically the same problem.
With one version I get passed the passphrase - but trying dumpprivkey and the result is: private key for address xyz is not known (code -4)
With the other backup (the one with the coins) - the passphrase is incorrect (code -14)

I think I found out how to do it https://bitcoin.stackexchange.com/questions/20869/how-to-get-private-key-from-litecoin-qt-wallet
Is it important on which wallet version I should work on (the one that accepts the passphrase or the one with the coins)?

Thanks! You've just given me new hope...
But, I don't know how to do the first part - getting the private key for the addresses containing the LTCs?
Can you point me to someone/somewhere?

Regarding the second part - can I install electrum-ltc-portable on the same machine, or should I install it on a different one?

After countless attempts to unlock my wallet, I am starting to lose hope 
The story in a nutshell: https://bitcointalk.org/index.php?topic=1887950.msg18754513#msg18754513

(I should emphasize that I set up the passphrase only once - so the different versions of wallet.dat derive from the same setup)

So I am offering a reward of 10 LTCs to anyone who will be able to unlock my wallet.

Thanks in advance
Don

Yes, I did. I actually made a few backups, so named them differently upon backup, and renamed to wallet.dat upon restore.




I actually re-installed litecoin on my desktop a few times, and also made a fresh installation on a laptop. Phase 2 was to restore the wallet - and on both machines I end up on the same bottom line; either have an empty wallet with the passphrase I set-up originally acceptable, or have a wallet that has my coins recorded, but will not accept my passphrase.

I contacted the exchange where I purchased the coins from (via a bank transfer), they confirmed that the coins are still in the wallet addresses given at the time.

Hi
I have recently installed Litecoin on my Win10 Desktop.
I have then encrypted my wallet and set up a passphrase.
After that, I made a small purchase of LTC.
As it happened, some issues on my desktop required me to format and reinstall Windows.
I've made a backup of the wallet, and after re-installation and restoring the wallet - everything seemed fine - except for an error message on which I did not think was serious - the LTCs were in place.

I have then decide to make another LTC purchase, this time a bigger one, which was successful.

After a couple of days, I installed a Litecoin wallet on my android phone and, in wishing to get myself familiarized, I tried to send LTC from my desktop wallet to my android wallet.

I was then asked for my passphrase - and to my great surprise got a message that my passphrase is incorrect.

After several attempts, including different possible passphrases, using a few backup versions of the wallet and reinstalling Litecoin wallet on my desktop, I have reached to the following 2 options (arising from different backup files - made from the same PC).

1. I have the coins in my wallet - but my passphrase is not accepted.
2. My passphrase is accepted - but my balance is 0.

Please note that with option 2 - i did not set up a new passphrase, the wallet is already encrypted - I am just able to change my passphrase.
This is the error message I receive when I recover the wallet with the coins in it:

The file was named walletrrstored.dat

Any help will be GREATLY appreciated.

Thanks in advance
Don