I already read the thread how to merge epub files but Is there any way by which I can merge different pdf files into one. Earlier I have tried an app for this purpose but I lost all my pdf files after merging.
A shameless plug for other who may have this problem in the future:
I built a web tool to merge PDFs for when I needed to bundle up some files. It's free to use and does not upload your documents to a server, so they stay private.