so where i can put the user download libraries ? YES i always restart my IDE after add downloaded libraries
before i got this problem
3rd party and user written libraries should be loaded into a folder named library in the user's sketch directory, If one isn't there then you need to create this library folder. Then specific downloaded libraries are saved in a folder with the same name as the xxx.h file along with any other files used by the library.
If you do install 3rd party libraries into the arduino core section the problem is that if and when you ever upgrade to a newer version of the IDE you will lose all your 3rd party libraries unless you manual copy them before you upgrade the IDE and then manual re-install them into the IDE's core library folder. The user's sketch directory is not erased when one upgrades the IDE so all your 3rd party libraries are not disturbed.