Radio code help please

After a recent power outage my stereo reset itself. Although the code is written in my manual in the glovebox I was too lazy to look and thought I could remember the number.

Needless to say I got the code wrong three times and now the stereo isn't even entertaining the idea of asking for a code. Does anyone know what I can do? I do love listening to music and it helps drown out the rattles and creaks

Many thanks

Off the top of my head
I'm sure it's 20 mins with the sterio left on
But some of them can be reset by holding 6 when you turn it on
That also gives you 10 mins with no code