etherbrat, I am sure you understand that if you install an app outside of the apt system, updating the apt database would be a very bad idea !
So, if you have a failed 'manual' install, you really must manually remove any part of it thats likely to get in the way latter on. Only then can you proceed to where you, perhaps, should have started from.
Right now, its great, FPC 3.0.4 has been around long enough that most distros are shipping it in their default model. So, using it is really the default way of getting going. But, in your case, you really must clean up that failed manual install first !
Did you run that manual install as root or yourself ? In either case you should try and find where it installed things. Generally, the problem will revolve around things installed on your path and /etc.
When its cleaned up, install FPC and FPC Source from distro's repo. Along with any necessary dependancies. Note: "pdkg install something.deb" does not resolve dependancies. Gdebi is a better choice. Then you have a couple of options to get Lazarus. Easiest is to use your distros offering. If its 1.8.4 maybe thats the way to go. Or download the deb from FPC/Lazarus website and use gdebi to install. Better, IMHO is to pull down lazarus src using SVN and build it in your own space, bit more flexible ....
Davo