Setting up Swap memory
 

Im trying to set up swap memory in linux( after O.S installation) , however it vanishes once the system is rebooted, Can anyone help me out how to make it permanent.

Did you create a swap partition or a swap file?

And if it's a swap file, where did you put it?

If you use systemd as your init system the swap partition will be mounted automatically, otherwise you need to add it to /etc/fstab
This presumes a swap partition rather than a swap file.

What precisely do you mean when you say that "it (I presume you mean the contents of the swap partition) vanishes"?

Note that Linux swaps only when it needs to. Unlike Windows, it does not swap just because it can.