so, a few years back, I set up bitcoin core on my computer, but I put it on drive D while Windows was on drive C. I had my password hints in a text file on C, but then I had to fix some issues with Windows and ended up formatting drive C. Now I've got a new Windows installation, and I've totally spaced on my wallet password. To make things worse, that text file is gone too. I've tried some recovery apps, but nothing's worked so far. I'm really stuck here, so any advice would be super helpful.
Find a professional data recovery company in your area and seek their help. If you don't know what you are doing, it's best for you not to try anything more.
Do you still have the wallet.dat file on the drive D?
If you still have the wallet.dat file you can brute-force the wallet only if you still remember your password partially.
Or hire a professional who can recover your wallet check this site walletrecoveryservices.com
This is the best option. There are many specialists who can dive deeper than recovery programs that you might be trying OP.
OP just so that you are aware, this will probably only work if you know some of the password or if the password is short (depending on your computer power). The more of the password that you know, the less time it will be likely to take to find the right password. If you take this route, there are some open source tools to help you efficiently give this a go.
Follow the first reply because what you've already done potentially destroyed the data that you want to recover from that drive.
What I mean is when you've installed the new OS or recovery program, it may have been written on top of that .txt file.
Even using the PC alone can overwrite those data since an OS isn't just all read process.
How about the data directory?
If you had been using the default, then it was also saved in C:/
Because you may have a bigger issue than a lost password if your wallet.dat file is also wiped.
BTW, how've you been starting Bitcoin Core after installing a new Windows? (do not try this now since it counts as using the disk)
Directly starting bitcoin-qt.exe?
Through a shortcut with command line option like -datadir?
Using cmd or PowerShell?