After i upgraded my s3 neo from jelly bean to lollipop all my apps were crashed, how can i downgrade it?
Is your phone rooted? If yes, then download any rom for your device of your linking from xda, and flash it. Follow the instructions on the forum to install the rom. If you're not rooted, then you will have to download the stock firmware from a site like sammobile,
Once downloaded, you'll have to download a program called ODIN.
Get the Samsung USB drivers for your phone too. Now the firmware file you download will be zipped, so extract it in an easily remembered decretory, like your desktop. Open ODIN.
The MD5 file would go into the AP box. Sounds weird, I agree, but the AP box will be your best friend. You don't need to worry about any other Boxes.
Once the file is in the box, you would now need to turn off your device, and reboot into Download Mode by holding Volume Down, the Power Button and the Home Button.
Press Volume Up to proceed to the actual Download Mode.
Once in Download Mode, you can plug in your device. You will need to wait several minutes, as ODIN, your PC, and the device communicate.
After some time has passed, upward of several minutes, you should see a box that is colored and has a type, and a number: eg - 'COM:3' That means your PC recognizes the device and everything should be ready to go. The number is irrelevant.
Note the COM:3, and the MD5 file in the AP box. Now, to begin, just click Start.
Do not disconnect the device from the cable until ODIN returns a successful message or a failed message.
When ODIN is done, you should see a box that will say reset or passed (depending on which version you have, you may see either or both.). At this point it is OK to remove your device. ODIN has completed the flash, and by now, the device should be going through the reboot screen.
Any problems, try these few things: Update Drivers, and restart your PC; Different cables; Different USB ports.