Steam not launching after switching Graphics Card?

I recently purchased and installed an AMD Sapphire R7 4GB 240. Ubuntu automatically switched to some Open-Source Drivers named Gallium 0.4 on AMD OLAND.

For some reason Steam is not able to launch anymore. I tried opening it from command line and this error came up:

Running Steam on Ubuntu 15.04 64-bit
STEAM_RUNTIME is enabled automatically
Installing breakpad exception handler for appid(steam)/version(1440016726)
libGL error: unable to load driver: radeonsi_dri.so
libGL error: driver pointer missing
libGL error: failed to load driver: radeonsi
libGL error: unable to load driver: radeonsi_dri.so
libGL error: driver pointer missing
libGL error: failed to load driver: radeonsi
libGL error: unable to load driver: swrast_dri.so
libGL error: failed to load driver: swrast

(Steam used to work properly)

I believe Steam was not able to find Official Drivers, since I did not install them, which I am unable to find. A DVD with those drivers was included, but it said "Windows XP,Vista,7,8". Not Mac or anything.

Is anybody who knows what am I doing wrong?

EDIT: I started it up with the help of irc.ubuntu.com with this article: ... but I can't start up any game at all

Second Edit: You can also tell me how to run games on Steam while running this following command:

LD_PRELOAD=/usr/lib/i386-linux-gnu/libstdc++.so.6 DISPLAY=:0 steam

EDIT 3: @SachinKamath told me to re-install Steam from the command line, after deleting Steam. (She was right, even though a Steam Launcher problem seems to appear)

But the following error appears if I run it on command line: Erm.. I got one problem..

Running Steam on ubuntu 15.04 64-bit

STEAM_RUNTIME is enabled automatically

[2015-08-26 17:07:59] Startup - updater built Aug 19 2015 11:27:40

SteamUpdateUI: An X Error occurred

X Error of failed request: BadValue (integer parameter out of range for operation)

(Was it a corrupted download? Perhaps?)

1 Answer

As mentioned in the comments, the solution is to remove the .deb file installed from the Steam website and do sudo apt-get install steam as it automatically installs the required libraries and packages required for the proper functioning of Steam.

Edit : Check out this answer to fix the Integer parameter error that throws up.