When ThePiratebay is down you may just use Google!
     
    Step 1 Google:
    site:thepiratebay.se "info hash" "your Search Term"
    example site:thepiratebay.se "info hash" "ubuntu 12 04"
     
    Step 2
    Copy the resulting infohash (for the example the infohash is 95CDB508E6B47B227D3AE1A462EBEF4E949F307D )
    and paste it in http://centrump2p.com/magnet/
    You get the magnet and that's it!
     
    :-)