If you have taken it down farther than you can remember how to reassemble it, it's time to take it to a gunsmith.
If you are determined to do it your self, there are several books on shotgun disassembly/reassembly. Check out DBI publishing or Amazon.com to find one which has your shotgun.
This would be a 12 ga. BPS (Hunter model) pump shotgun made in 1984
50-500 usd
50-500 usd
It came with the Invector system which allowed changing chokes.
Ask a gunsmith for help or download a manual for free on Browning's web site.
Browning has manuals for download on their website or via USPS for free
A Browning field model bps shotgun is worth between 170-265 dollars for a shotgun with between 60%-90% of its original finish remaining,and a good bore.
Depending on condition $300-$450
Depends on condition and whether it has the original box and papers.
Browning Pump Shotgun "BPS"
1991
Seems about 50.00 dollars to high