Advice needed please help

i have an acer aspire 5315, i used a password on the hdd security option in the bios and now cannot remember the password! i have tried all of usual passwords and none of them worked. as a result i get a message after every third password attempt which says encrypted hdd key 10979631 i am not able to access the recovery through alt F10 and cannot start up can anyone offer any advice on how to get round this problem. please note i do not have a recovery cd (i know...totally stupid of me lol)