Samsung Galaxy Y Plus (GT-S5303) Firmware Overview
What is the latest GT-S5303 firmware?
S5303XXAMK1, released November 15, 2013 with Android 4.0. The archive holds 2 official builds across 1 region (CSC). Each one is the full stock ROM (flash file) for Odin, not an OTA patch.
Is the Samsung Galaxy Y Plus still getting updates?
Most likely not: there has been no new firmware since November 2013, so Android 4.0 is the last version this model got. The final builds below are still the best choice for a clean reinstall.
All GT-S5303 firmware builds
How to Flash GT-S5303 Firmware
Put the Samsung Galaxy Y Plus into Download Mode, load the BL, AP, CP and CSC files into Odin on a Windows PC and press Start. Use HOME_CSC to keep your data, CSC for a full wipe.