My PC is recently scanned and it has much viruses. After that, I open a pdf file. It opens but the text in the file is incorrect. It seems to open another file.
If you are viewing the PDF in a browser you may just need to hit refresh.
There may be chances of virus infecting your PDF file and antivirus has corrupted that file.
Now, check your adobe acrobat reader software by opening other PDF files. If it's opening other files correctly, your PDF file is corrupt now. And if you're unable to open any PDF file, re-install Adobe Acrobat reader.
Or you can try Foxit Reader. Your PDF files may require some font or plugin to open. Foxit will direct you to install, in that case. Check out http://www.computers.helpof.com/foxit-reader-for-windows-free-pdf-reader/
Hope it will help you.
Well, it sounds like your issue with the PDF file is a secondary problem. You should tend to your main problem first, i.e. getting rid of the viruses on your computer.
I would recommend to backup your data and completely wipe and reinstall your system. You didn't specify your operating system, so I'm suggesting two potentially relevant articles, one for Mac and one for Windows:
For future virus protection, please consider the answers to these questions:
If you must open the PDF now, you have several options. Which software are you currently using? I suppose it's Adobe's free PDF Reader.
1. You could use a different PDF viewer.
2. You could eMail the PDF to your Gmail account and open it within Gmail.
3. If you don't have or want Gmail you could upload the PDF to a free file sharing website and then open it with Google docs viewer.
4. You can use online PDF viewers, to which you must first upload the file.