Generally, in a wordpress website we use few menu items and their submenus. We can create menu dynamically through admin Appearance => Menu Section and add the items as per our choice.
Sometimes, we need to add more menu items. Suddenly we face a situation that the item we are adding start replacing previously added item. It means we are unable to add more menu items in this case.

Actually in this case we have reached a limit of addition of more menu items in wordpress menu. In most of the cases the limit is about 90 items per menu. As we must need to know this is not a limit by wordpress, this is due to our hosting service. Hosting server limits this due to some security reasons.

To solve this, we need to follow few simple steps :

1. Go to root of your wordpress files
2. Search for php.ini file in your wp-admin folder
3. If you are not able to find php.ini file then create a php.ini blank file and upload it to your wp-admin folder
4. Now, put a small code snippet to increase menu items limit, that is : 

max_input_vars=5000;

5. Save the file and then upload it again

Start adding new menu items to the menu you want, it will work perfectly. We just need to increase limit my increasing max_input_var through php.ini file. There are few more ways to increase the limit, but I am discussing the one through which I have resolved my problem. If this will not work for you, then contact your hosting providers.