STOP!

First of all, one doesn't "clean out" a fuel filter, it's replaced with
a new filter.

Since you opened the fuel system it must be purged of air; this can be
done with the hand primer pump that's probably below the injection pump.
(I don't know this model). Look for what appears to be an 7" x 1.5"
aluminum pipe pointing at you that has a round black plastic top.
Unscrew that top and start pumping to draw fresh fuel into the filter(s)
that were emptied earlier. It should be fine after ten or twenty
strokes, screw the top back on to the hand primer pump.

Then, leave the fuel system alone; that's probably NOT the problem.

Diesels use glow plugs to heat their cold cylinders prior to starting;
that's the light with the coiled wire that's on the dash - it ought to
light for about 10 seconds when the key is turned ON and then go out
signaling the engine is ready to be cranked. There's a glow plug relay
and on it, a metal fuse (fusable link). Chances are that if this is the
first instance of no starting the link is broken cutting the power to
the glow plugs.

The engine won't start without working glow plugs. So you need to
investigate them to ensure they are working. Start by finding the glow
plug relay - trace the wires from the glow plugs - 4 wires on the side
of the head, near the injectors - back to the relay. The glow plug relay
may have a plastic cover over the link. Replacement links are available
from a M-B dealer and others for about $1 or $2 each - your car needs
one - plus a spare.

If you are confident that the glow plugs are working but that there's no
fuel being injected then the next suspects are either an air leak in the
fuel system or that the engine's vacuum powered shut down device no
longer releasing when you want to start the engine. Air leaks are fixed
by being sure all fuel hose connections, filters etc. are secure. The
shut down device is of the "right age" to be suspect. Its a small
bellows that's on or inside the injection pump that pulls the fuel rack
to OFF when you shut down the motor. The bellows wears out, gets oil
logged and fails. Usually the engine doesn't stop and needs to be
stopped by pressing the STOP lever on the throttle linkage.

Diesels are simple motors to maintain. Change the oil, change the
filters and leave them alone.
Hope this helps you.

I have a 84 190D too.  MB diesels in this OM60x series (e.g. 601 in 190D
2.2; 602 in 190D 2.5; 603 in 300D/300SDL/350SDL) no longer use the hand
primer pump.  Just crank it hard.  It may take more than 2 minutes to
fill up the entire fuel system if you ever let the fuel tank run dry!  I
thought replacing the filters won't drain the entire system, unless you
really let it open for extended period.

Glow plugs are important to get it start.  The relay is on top of left
front wheel well, a black box about 4"x4".  Check the fuse strap (80A,
$1 part), and check the resistence of each plug (should be around 1 ohm).

Injectors may be dirty but I would leave them as the last resort.  One
injector failure will cause rough but not no start.  Multiple failure is
unlikely considering it was running fine.

If the car has been sitting for 5 years, I would change all fluids (oil,
ATF, brake, PS).  Note that most motor oils are for gas engines.  You
need one that meets Cx spec (compression, instead of Sx spec, for
spark).  ATF is Dexron II.  Also, MB recommend changing brake fluid
every two years anyway.  And I believe MB calls ATF for the power
steering fluid.