How can I launch GTA IV?

[pepê balada]

I'm having some issues when lauching GTA IV on my PC
The Rockstar app runs but does'nt launch the GTA IV. Then in steam app appears that the game is able to launch it again

[Yujah]

The RGL (Rockstar Games Launcher) does at the moment semi-frequently fail to launch the game when started from Steam; have seen it happen here as well as of late. What hasn't failed for me is if I launch the RGL standalone and then "Play on Steam" the game from it. If that consistently works for you as well then I'd write this off as some hopefully transient RGL problem that will go away again after some more updates to that fine, fine launcher.

If you also can't start it from the RGL you have a different issue; in that case please verify the install from Steam (rightclick in Steam library -> Properties -> Installed Files -> Verify). If that finds something amiss it'll redownload stuff -- and if it then still doesn't work, please verify again: if Steam then still finds missing/damaged content you will have a fine, fine virus-scanner fuc... fining up things for you; has also been reported lately.

Finally; if also not, maybe try reinstalling the RGL clean: https://support.rockstargames.com/articles/16957180429203/How-to-perform-a-clean-install-of-the-Rockstar-Games-Launcher