How Can You Unformat Accidentally Formatted Memory Card?

Which type of memory card u r using ?

Not simple. SD/flash cards (current ones at least), will write data to new sectors in order to minimize the number of writes to any specific one (necessary to maximize the life-expectancy of the device). IE, the data is still there (most likely). Unfortunately, it requires special tools to search and find the data on those old sectors, and equally unfortunately I don't know what they are, except that they do exist. A data recovery firm that has such tools may be able to help you.

I use the third party software Power Data Recovery.

PhotoRec should be able to recover any files that are still intact.