INDIRECT FUNCTION - Make Data Stay Permenantly

I have approx 500 workbooks which contain custoemr details and I need to extract certain info (postcode, name, contact, phone number etc) and place it all on 1 spreadsheet. I was originally going to source data from unopen workbooks, but have realized I only need to do this task once, and I can maintain it from then on...


I have created a spreadsheet (attached) which uses INDIRECT formulas to retrieve the data. When I type in the file name in column A, Columns B to K fill themselves in. What I want to know is:

Once I open say, 10 Workbooks, TYPE the name in manually and all the other cells have filled themselves, I want to somehow KEEP the data there, rather than it return a #REF error when I close the workbooks to open the next batch.

Also, if you look at my workbook, to the far right is a range of data which I use in my INDIRECT formulas. Once I have filled all the cells with the relevant data, I want to be able to Filter my spreadsheet by Date Ascending. BUT I cant seem to do it because it includes my INDIRECT range in the filter and mess's up the formulas then I have tried Locking & protecting workbook, with Autofilter & select cells etc TICKED for users to use, but it still tells me to unlock workbook when I try to filter.