This is a bit old school phone. But I have still decided to make a tutorial just for the people that do not know how to hard reset / factory reset their Samsung Galaxy Pocket(S5300).
This procedure is almost identical to high end phone like Galaxy S3, Galaxy S4 and other Samsung devices.
NOTE: As I have always said, this will erase all your data such as contacts, messages, pictures, mp3 etc.. etc..
Here is the procedure
1. Turn off your phone
2. Press and Hold VOLUME UP + Home Button + POWER Button
3. Release the button when you see the Samsung Galaxy logo
4. Select wipe / factory reset, to navigate press the volume rocker, to select press the Home button
5. Reboot your phone
NOTE: If the process did not succeed you need to wipe the cache first before performing a wipe / factory reset.
I hope this tutorial help you.