Originally Posted by
acme266 My mobile have a lag so I want to reinstall my android, mabye it will fix a lag..
Welcome to the forums!
Rather than re-installing the software, try clearing the cache partition first then a factory reset. If that doesn't work, then try installing the factory firmware.
To get into recovery to clear cache: power off. Hold volume down+home+power button until recovery loads. Use volume down to highlight clear cache partition and power to accept. Let us know if that works.