Flashing the Galaxy Y using Odin back to its Stock ROM
*Do it on your own Risk.Me or the Devs of the linked pages below are not responsible for any mistakes you commit
and damage you bear to you device
*First Download your Requred Stock ROM based on your country from the below link
*Secondly you should have ODIN Get it from the below link
*Kies must be installed in you PC then only you can get the connectivity driver for your device
*Then what your samsung galaxy y and its data cable to connect with your PC
*Close Kies and better terminate it by CTRL+ALT+DEL and opening Taskmanager>>Processes>>KiesPDLR>>rightclick>>EndP rocessTree
*Open ODIN in your PC
*Select the necessary files to PIT, BOOTLOADER, PDA,PHONE (MODEM) and CSC.
*Check Re-partition, AutoReboot and F.Reset Time.
(Only for flashing Stock ROM completely.For Flashing baseband and CSC alone you dont need to repartition)
*Dont Connect your Device Now.
*First Switch off you Device
you can even select "Reboot in Download Mode" from the Boot menu of your Custom ROM
But this method is not quite advice-able coz some custom rom doesn't allow to boot in download mode so switch off do it manually
*Now turn on you device in Download mode
Do this by simply pressing the Volume Down+Power Button+Home Button simultaneously
till you see a warning
*Press Volume Up to continue to Download Mode
*After seeing Downloading connect the Data Cable to the Device
*See the ODIN on Your PC
*You will see the port number highlighted in yellow colour if your device is connected properly
*Now select Start and dont disturb both the device and your PC.
*After you see PASS in ODIN your device reboots and do a small installation in recovery mode and then it reboots automatically you have to do nothing.
*After you see that your Device is booting you can disconnect your device.
Thats it you had flashed the Device with Stock Rom which you can even update using Kies.
Hit thanks if you find useful
Got lot of help from many devs of xda