My Pentax K1000 won't flash when taking the picture

SOURCE: lens damaged camera dropped camera

"To get the lens to retract, we tried to do a slight twist over to the left (looking at the camera like your the subject - camera lens is facing you). Sure enough it went back in! But now it has trouble focusing. That's another question now. Darn thing...we'll see what else we can jimmy :-)"

quoted from another solution.

SOURCE: What kind of battery does the pentax k1000 35mm SLR camera take?

Yes the K100 uses LR44 or G13. I would recommend the G13

SOURCE: Pentax K1000 back door change

I don't have the solution, but it may be in the Pentax K1000 Service Manual that you can get here : http://www.robertstech.com/manuals.htm

SOURCE: Pentax K1000 rewinding knob restore

Pentax fan

There is a spring in the way. straighten a paper clip and from the top of the camera push it out of the way while you gently push the shaft up. rotating the shaft helps.
or you could file a little of the shaft collar on an angle ( if it's not there ) then rotate the shaft while gently pushing up. don't bend the spring.

SOURCE: on my pentax k1000 the black fuzz looking stuff

That's the mirror bumper, it softens the blow and cuts the noise as the mirror flips up.

Carefully remove it and then replace it with a new one. You can get it as part of a foam light seal repair kit for your camera; this also ensures that the sticky black goo which used to be foam and which prevents light from getting past the edges of the camera back gets replaced. Light seal kits are very cheap, and if you buy a pre-cut version then it makes a fiddly job a bit easier and potentially less messy. They're widely available on sites like ebay, just search for "k1000 light seals" and check that the kit includes a mirror bumper/buffer.

If you don't get it repaired the fuzz will get everywhere and can also get onto the film surface causing white spots on your photos or black spots on negatives/slides. The debris can also get into your lenses so remove it asap. Gooey foam light seals are even worse as it's both corrosive and abrasive (due to the grit it attracts) and gradually migrates to gum up the works. It can also result in light fogging on your photos (usually seen as red streaks from the top or bottom of the picture). Modern foam seals do not decompose like the old ones did.

I hope that I've helped you, please take a moment to rate my answer.