Invalid login details WP Admin

Up until a couple of days ago I was able to login to Wp Admin with no problems, now suddenly it will not let me in I just get “Invalid Login Details” even though the details are correct. I have clicked the forgot password link but it doesn’t send a reset password email to me.

Please help I need to update my site and as a customer has asked for a download version of a product and I am unable to do this for them.

Thank you.