Uh oh! It happens, though. So let's get this sorted for you.
First thing's first. You need to figure out how you signed up to our app. If you used Facebook, you'll need to sign in using your Facebook account. If you signed up with your Google Play account, you will have to use that account. And finally if you signed up with your Apple ID you will need to use that option.
There's no way to sign in with an Apple ID on an Android device, but the rest of the options are multi platform.
If you signed up directly with your email address, you can easily reset your password from the sign in page directly within the app.