So, I was using .7.4 and it wouldnt render in 16:9 ratio, then I upgraded to I think .7.5, and used force pixel aspect ratio on it.

It worked wonderfully, I as finally getting great videos out!

Then last night for some reason the upgrade to .7.6 it uninstalled itself, and today when I tried to edit a video it was no longer here. So I reinstalled it through synaptic and got .7.6

Now it wont render in 16:9, has these anoying black bars ontop and bellow the video, when I force pixel aspect ratio on it it doesnt work, and in general crashes a lot more than .7.5 did.

HOW CAN I GET .7.5 BACK?

I just want to uninstall it and go back to the version that worked right, as this is very time sensitive and I need need need to get these videos done, money relies on it.

I just want to install .7.5 back and get rid of this newest version that doesnt work at all.

A lot of people complained about the instability of 0.7.5. A lot of work has been put into stability in 0.7.6 and already we received positive feedback about it. I would say based on that and because forcing aspect ratio works for me (I just tested it), there might be something wrong with your install. Maybe you have more than one installation of MLT. Before giving up on your aspect ratio problem, try this. Right-click on the clip in the Project Tree and choose Reload Clip. Beyond that, if you still want to try to downgrade, I suggest you ask in the "Installation from binary packages" which the packagers tend to monitor.

As Dan said, I think Kdenlive 0.7.6 should be rather stable and if you experience frequent crashes, that might come from an installation problem.

First, make sure which MLT packages are installed. In Ubuntu, from a terminal:

sudo dpkg -l | grep mlt


Then, if you experience a crash, we need precise information on how to reproduce.

nunki says Kdenlive "crashes every time I try to render the project in DVD/PAL 16:9". I don't think it is possible, since the rendering runs in a separate process which cannot crash Kdenlive. So maybe he meant: the rendering fails saying error xxx. That is NOT the same thing.

Rendering can fail or crash if you have missing codecs or a problem in your ffmpeg installations.
If for some reason you really need to go back to a previous Kdenlive version, you should be able to do something like that:

sudo apt-get install kdenlive=0.7.5