Backup problem

The majority of users here are using U.S. versions of Quicken, so definitive answers may be difficult to get.

My response is based totally on U.S. versions of Quicken.

You can check this Intuit kb article to see if anything applies to your situation.

This should be impossible. Windows does not allow two files with the same name.extension in the same folder.

The QDF, QPH, QEL files are part/all of your Quicken data fileset [QDF contains most of your data; QPH contains security price history; QEL contains online info]. The IDX file is an index file created by Quicken, it does get backed up, but nothing is lost if you don't have it ... Quicken will create a new one next time it opens that fileset.

I don't recall any version of Quicken ever having an HCX or a QIN file; perhaps they are left over from some time in the past or some other activity besides a Quicken backup. [Q2007, US has an NPC file whose purpose I don't know, it's always been empty for me. That file is not present for Q2008]

In the U.S., if you had used the Quicken Tax Planner, you'd have a QTX file in the fileset.

You could recover the most important part of your data if you had only the QDF file (Quicken will recreate any other files, but they will be empty). Still, the best bet is to have all the files that Quicken creates when it does a backup.

You do not need to know which Windows files are part of the fileset; in Quicken, you always work with (specify) just the QDF file. If you want to Backup, Restore, Find, Open, etc., you specify the QDF file (its name, such as "QDATA"): Quicken knows what other files are part of the fileset and either opens them if they're present, or creates new, empty, files if they are not present.