I will post the solution in case someone needs it in the future.
First of all i would like to say that nvram-clear and nvram recover didn't work for me even though I tried numerous times.
Now in recover mode I was able to telnet and inspect the nvram.
Sure enough all dd-wrt stuff was there (including encrypted username and password).
I tried resetting them to be blank , but that didn't help either.
Then I decided to try and install the stock firmware.
Strangely this one worked and I was able to login using default username and password.
Just in case I used reset to factory defaults and then reinstalled Oleg's firmware 1-9-27-10 and now I am able to login.