roslaunch can't find package
Title says it. It just is not working. I've been all over the internet, and yes, I did source the devel/setup.bash, and did add the sourcing action to the ~/.bashrc, and I've been stuck in here for 3 days now. Please, if you have any clue what's going wrong, let me know. Ask for any further details.
well .. please begin by explaining (and showing (just with text)) what it is that you're trying to do exactly.
No paraphrasing of errors. Just copy-paste commands and their output.
Tell us which OS this is, how you've installed ROS, the layout of your workspace, a bit about which packages you're having trouble with, which commands you use to create your workspace, how you build it, what you do after it has been built, etc, etc.
There is no magic wand we can wave and fix it for you.