computer said the crank sensor was bad, replaced it, but didn't fix problem on 2002 Honda Civic

after car warms up, doesn't seem like it is getting any fuel. doesn't go over 20 to 25 miles an hour even if I floor it!

There's no computer that will tell you the crank sensor is bad. The info a professional tech gets from a professional scanner(computer) provides the info to perform proper diagnosis. Take it to a professional.
Thank you for your response. I took it to a mechanic, who I thought was a professional? The crank sensor was the diagnosis per the mechanic per the computer, and now he is talking maybe having to replace the computer, but was going to do some more research? So, after he said that I am trying to do my research, too! The malfunction light came on immediately when it happened the first time, and never before has given me any indication that something was wrong. Does a computer go wrong that fast?
Anything is possible in this business.
I believe that is true in life! Thank you for your responses!!