I cannot login in admin and my clients cannot login

I dont know what happened all suddenly i cannot login in my admin page and my clients cannot login. They can register and they get an email saying they are register but when they try to put in their account info it goes no where. Also my admin too. I cannot login but if i put in a wrong password it tells me the password is wrong. When i do put in the correct password it does nothing. Can anyone help?

thank you
jaz

Hi
First ask your hosting company have they upgraded there php or mysql if yes then what is current zencart version unless you provide details can;t help much

if php has been upgraded to php5 then you will need to upgrade zen cart to latest version

else search the forum for session settings you will find the solution
also in faqs the solution is available
thanks