help - car won't start

car's been parked up for five days. just got 2 toddlers and a baby all strapped in, and it won't start. It's turning over but not firing. It's a warm day and I turned it over plenty of times so it can't be that it's cold (more likely by now that it's flooded but that wouldn't explain why it wouldn't start in the first place).

Had the cambelt changed the other day (thanks for members that gave me advice on that - I phoned round and got quotes from