Can attach the Tableau Data Source page if possible?
If the data sources you're connected to are published on Tableau Server, you'll need to download the data source itself to be able to get an understanding of what they connect to. You can't see this information via the workbook.
Depending on your access, you may not have the rights to do this, so you'll need to discuss with whoever created the data source.
At desktop app, open the workbook and make a "local copy" of data-source.
After that, replace the data-source whit this local copy.
At this point, you can see the query's again and you can make your analyses/changes.
After that, you can replace your on-line copy of workbook and data-source
This procedure not is so friendly, but worked for me.
Glad to know you're sorted Rajesh. I have taken the liberty of marking this thread as 'Assumed Answered' so that it's removed from the unanswered questions 'pot'.
.tdsx files always have the underlying SQL querys.