Q: I have forgotten apple id and it's password while i cloud asked me that

I have forgotten apple id and it's password while i cloud asked me that.

on the other hand i have been forced to restart my i phone that after that i flash my i phone.

Now i want to run my i phone but i cloud asked me apple id and password which is not available.

how can i run my i phone?

Unfortunately i can't use from my i phone 6.

your prompt response would be highly appreciated in advance.