What is the possibility for get back the password if I have no idea for the password
Just the possibility
Well.. this depends on the amount of time you are willing to invest to crack your password.
The time is basically depending on 2 factors:
- Amount of passwords to check (which itself depends on 1) password length and 2) the set of characters used)
- The amount of combinations your machine is able to test
For example:
If you were using 0-9, a-z and A-Z.. thats 10+26+26(=62) different characters.
If you only remember that your password was between 6 and 8 chars that would result in
62^6 + 62^7 + 62^8 (=221.918.520.000.000) possible combinations you would have to try.
On average you have to serach 1/2 of the search space to find your password (50% chance after 50% being tested).
Thats still quite tough.
The more you remember from your password, the easier it is to reconstruct it.
I'd say anything above 8 characters is not possible to crack in an appropiate amount of time (currently).