I can only imagine how challenging that situation must have been for you not being able to connect your web connector, @sandeep117.
Let me make it up by ensuring you get a detailed explanation of why this issue occurs.
Firstly, I would like to ask if what QuickBooks version you're currently using?
Compatibility issues can cause the error you encountered while connecting to the web connector on your QuickBooks Desktop (QBDT). It could also be because the web connector isn't installed in the same location as the QuickBooks file.
Let's ensure that the location of the web connector is the same as the QuickBooks file. For this to be taken care of accordingly, you can download a web connector again that depends on your QuickBooks Desktop version.