Unable to open my PC with my password?

I have an Amilo Li2727. that I cannot operate
My problem is a need to open my Laptop but my sign in password is not accepted, it was fine for over a year
PC asks for correct password
Can I reverse this or creat new password to open

Thank you,

As I cannot open I am useing a library PC

Would apriciate text response on 0796 002 8854