Login to my iphone zoho mobile app not working

Login to my iphone zoho mobile app not working

I was using my mobile app on my iphone and it is great! I logged in once and didn't have to again. Today the app is asking for my login information, user name and password which I input, but I am being told invalid user name or password.  My account is fine online, but not on my phone anymore. Can you help?
 
Gail Breakwell
Adam Chahl Real Estate Group