What is a flash file or stock firmware ROM? It is an OS which you installs like windows in your PC.Download Flash Files from below and follow the instruction listed below.
Download Flash Files-
Note: Before installing flash file to your Micromax A24, please backup all your important data and files to your other smartphone or laptop.
Here is an another article you may want to read- Micromax Bolt A24 Hard Reset and Unlock Google Pattern (Verified)