Scotch tape! Transparent tape exact width of watch face. Apply similarly the same way you put screen protector on electronic devices. Cut 1 piece about 3 in. long, center & place on face first then push out air bubbles. If one band connector can still be attached
align it first and tape. The broken band then must be held in place to tape. I have an over lapse of 1 inch tape on each side of the watch face . Tape additional excess length to the bands. I thought this would a temporary fix but I’ve only had to replace tape after I got it wet. That was after 3 months. I do dishes and wash face daily with my watch on. I quit doing that and the tape looks undetectable. I can still use different bands that I have if I want.