Memory loss is unusual forgetfulness. You may not be able to remember Mobile Numbers, new events,or more memories of the past, or both.
The memory loss may be for a short time and then resolve.Or it may not go away and depending on the cause, it can get worse over time.
You can improve your memory with playing games, meditation, yoga etc.
Doing activities that engage your brain, such as Sudoku and crossword puzzles, and reading in general can also help improve your memory.