I have tried all of the above and the problem of not being able connect to the ipod touch continues.
In addition I have contacted Apple's tech help and I did whatever they suggested. These are
(1) to do a hard reset (by pressing the home button and the button at the top simultaneously for 5 seconds)
(2) re-install itunes in my computer
(3) connect the ipod to the computer with another chord or cable
(4) re-start my computer
(5) connect the ipod to another USB port
In two days I am taking to a store here. If there is a solution I will post it here.
Till about a month or so when the new itunes came on, the device was working well. The version I am running now is 12.3.2.
If the new version of itunes is not able to connect to the old ipod touch. Apple, then, should not ask us to upgrade or they should make the old version available.