The other day I was going to ride my 1999 Gary Fisher Joshua F4 mountain bike and when I started riding it I could upshift with the RD,(would shift to the smaller gears) but I couldn`t downshift so I`m thinking maybe the shifter is messed up somehow. I don`t know if the shifter broke or cable broke. Is it maybe an easy fix? Here are some pictures of the rear shifter and RD. I just hope someone knows whats wrong and can help, thanks

That looks to me like a pretty lightly used bike. I doubt you have a serious mechanical problem.

My guess is that the grease in the shifter has hardened. A common solution is to find or open a window into the internals of the shifter. Give it a good spray with WD40 or something similar and try working the shifter. My bet it that'll fix it.

I took a closer look at the cable and it is shreded on one end. Don`t know how I missed that earlier but thanks I did put some grease in the shifter while I had it apart Retro Grouch. Here is what I found.

Well, that would explain it. Instead of pulling cable, shifting will only keep collapsing the housing. A replacement is in order.
I wonder how that happened.

Don`t know how it happened but the end that goes into the cable holder is just all shreded up. Its like the plastic got broke right there somehow I guess.

I've seen that before with older shift housing; it happens, you just have to replace it. With a bit of care an attention to detail, it's as easy as replacing a chain.

Is it possible you have a 12 year old bike that's never been ridden?

That looks to me like whoever put the shift housing ferrel on did a lousy job. In the normal course of things that would have been done at the factory. I'd think that a mistake like that would have been caught when the bike was packed into the box for shipping or certainly when the bike was assembled at the dealers.

A couple feet of shift cable housing and a ferrel end should fix it.

It has been quite a while since I have rode it, maybe 7 or 8 years and it shifted fine then. I have been riding my road bikes and decided to hit the woods and then that happened. I guess maybe I should take it to the LBS and let them check it over.