.

[Ste3001]

.

[Csmiami]

I'd reccomend you to contact Keychainx, I did some work for them and are a good team

[Welsh]

You've only got 43 letters out of 64? Then, that's not going to be possible to brute force, and would likely be a waste of resources for those that try. Not only that, I don't think I'd be in a rush to trust anyone with my private key. Do you have the wallet file, or any other way of getting into the wallet?

[LoyceV]

only 43 letter - numbers...

Which private key format is it? See [overview] Recover Bitcoin from any old storage format: the most common WIF format has 51 or 52 characters, there's also a less common 44 character key, and 64 is a possibility too.

What's the story behind losing the characters: do you know the exact location, do you know for sure the rest is correct, and are they missing at the end (which is the checksum)?
A bit more information is useful, and be careful who you trust (scammers can PM too).

[Matt9301]

I have lost some letter - numbers from my private key!! i have all my public key and only 43 letter - numbers...
Dm me please if someone know how i can (bruforce maybe...) retrieve all my private key??
I will give to him small reward....
Thanks!

It's so difficult to bruteforce, but I have a question, are those numbers consecutives? If yes, there is a little way to solve it, but it means to wait some weeks. Have you your wallet.dat file?