DSL only requires the same two wires that make your 'phone operate, and if that still works it's not likely to be a connection problem.
As you've tried with a different router, a different micro-filter, and you've tried the internal 'test' socket, with no results, it looks like the ADSL service has been ceased on your line (or there's a fault at the exchange).
Ade
Giving UKFSN/Entanet a try - 1 year and counting!
DL Sync 4000kbps
UL Sync 448