The Mileage and clock are flashing on and off together = Dash isn't Proxy Aligned (ie the dash isn't communicating / sync'd up / talking the same language to the car
It needs to be plugged into a a decent snap on code reader or to an auto sparky
It may explain why the speedo dont work
But it dont explain why it suddenly lost its sync either
it could also be hinding other issues - like a bust speed sensor
Are you a ABS or non Abs application?
What works happened recently to the car?
Ziggy