Restarting my carrier as s/w engineer

HELLO ALL

A VERY HAPPY NEW YEAR.
I JUST WANT GUIDANCE RELATED FOLLOWING POINTS
1)AFTER 6 YEAR GAP.FROM WHERE TO START PREPARATION FOR INTERVIEW
2)CHANGES IN S/W FILEDS IN LAST 6 YEARS...(IN DOTNET TECHNOLOGY)
3)CHANCES OF REJOIN THE COMPANY

WAITING FOR REPLAY
HAVE A NICE DAY