Help Samsung S5 - Forgot Alternative password - no data

[weewill]

Hello
Hoping someone can help.
I've managed to lock my Samsung S5, after trying and failing to unlock with fingerprint recognition for some reason it is now asking for " alternative password " , I cant remember setting one up . so I don't know it.

I have tried to unlock via Google device manager .
However my phone doesn't have mobile data turned on and the screen is locked so I cant turn data on , is there any way to unlock it or turn on mobile data with the screen locked ?

Any help would be greatly appreciated !
Many Thanks

 

[Pugs1957]

Are you able to see the phone in Android Device Manager?

 

[funkylogik]

Isn't the alternative password your Google password?