as my car was working ok and suddenly speed became slow but accelerator is ok

What is your question?

as i am using this car and there was no problem at all,as today when i fill up petrol and after 8 to 10 miles running very slow as accelerator is ok if i accelerate its going ok but the speed became very slow and petrol consumption increase as its in 14 miles 2 unites of petrol drop which is not normal for toyota prius. as when i speed to 30 its look like that speed of 10 to 15. can you please guide me what to do in this situation?

What makes this problem better or worse?

engine and oil is ok

How long has your 2003 Toyota Prius had this problem?

as it,s start today from mid day.