If you have a google account connected to the phone you can use android device manager to reset the password....https://www.google.com/android/devicemanager then sign in with your google account and password. Then choose lock, then google will ask you to create a new password. Then you can use that password ***** unlock your screen on the S5.
If you can not do the above you will have to do a factory restore on the phone>after the restore you can sign in with your account and restore your contacts and data.> Please follow these steps>
i am not even sure of my google details either