Here I will explain how data recovery apps like recuva & easeus works. The concept behind these apps will be explained here in detail. But first I recommend you to read the following questions answer it will help you to understand this concept in a better way.
How a data is stored in memory ?
Everything stored in memory is given an address to access stored data whenever it is needed by our computing system.
What happens when we delete a data from it’s location ?
So as you delete data from its location it is transferred to recycle bin and allotted a new address.
What happens when we restore a data from recycle bin ?
When you restore a data from recycle bin then again that data gets its previously allotted address. Then you can again access those data from the previous location only.
What happens when we delete a data from recycle bin also ?
Now when you delete a data from recycle bin also it don’t get vanishes in the air but its address is been erased & it don’t get any new address allotted. So you cannot now access those data.
Memory without address are kept to reuse it & write new data & allot it a new address. Until a new data is written over the previous memory allocation the previous data can be recovered.
So it is advisable to stop any downloading & installing process after you permanently deleted a file by mistake. So data can have greater chance of recovery. Otherwise it may be possible that new data is been written over previous one thus making it impossible to recover previous data.
So how to restore permanently deleted data ?
To know answer of this question click on the link given below :
It is also advisable that you should always keep these software preinstalled. To minimum the chance of data loss during recovery on the basis of answer given to the previous question.
So how do these data recovery app work ?
So these apps simply scan your memory & if they find any location with stored data but no address then it will allot new address to it. Thus making those data accessible.