Connection time
 

I have planned to travel from Dhaka to Memphis on 12th august via qatar airways. Through this trip i need to go through chicago ohare international airport and the connection time will be 2 hr 20 min. I'll land on chicago at 14:35 and American airlines will provide that flight from chicago to memphis. is that 2 hr 20 min enough for switching one airline to another with luggage ? Thanks in advance.

You will have to clear passport control and customs in Chicago, and change terminals. I would want longer, unless I had a US passport and Global Entry.

If you have an ESTA, you can clear immigration and passport control quickly using the kiosks but it might take ages to pick up your luggage, get thru customs, drop off your luggage again for the next flight, get to the other terminal. It might be enough time, if not and you miss the next flight, there are 4 flights a day so hopefully it won't be too long before you are on the next available one.

The trouble with the "next available flight" is that so many flights these days are fully booked or oversold. The next available may be the next day (just ask Dr. Dao).

Also, the OP is traveling from Bangladesh. If he is a Bangladeshi citizen he is not eligible for ESTA.

I assume you are buying your ticket from Qatar air. It sells the entire route to Memphis, including the American Airways leg. It is quite possible you will retrieve your bags at O'Hare, take them through US Customs, and recheck them at a nearby agent to go on to the final destination, since they are already tagged. It's not the same as going through a complete check-in process. However I have not flown this route. You can get in touch with Qatar and ask them, rather than dealing with a stranger's guess. Also ask which airline will be responsible if your connection is delayed

It is not "possible" that the OP will need to clear customs in O'Hare, it is certain. That is how the US does things. He will also have to clear passport control, and how long that will take is unpredictable.