Take a look to the "Using Windows Search To Search Inside PDF Files" section of this article https://www.online-tech-tips.com/computer-tips/how-to-search-for-text-inside-multiple-pdf-files-at-once/ (scroll down).
Basically, you have to:
Go to Control Panel > Indexing Options and click on Advanced,
Select the File Types tab on the following screen and look for pdf in the list. Tick-mark the box for pdf. Then enable the Index Properties and File Contents option and click on OK
Add the PDF folders into the index list. To do so, open the same Indexing Options dialog box and click on Modify. Then choose the folder where your PDFs are and click on OK to get the folders added for PDF indexing.
Once Windows has finished indexing your PDFs and their contents, you’ll be able to search for text inside multiple PDF files at once.
I tried all these options, But, Searching by this ways is limited and they do not give suitable results, also, they do not efficiently of Mendeley program. But, the Mendeley makes the computer weak
I previously used google desktop but did not get an intact version (all versions are invalid)