How to recover the deleted data in Salesforce?

Salesforce Record data has three stages of deletion. Data is recovered depending on the stage it is in.

Stage 1 - Deleted to Recycle Bin - Data in this stage can be recovered from the Recycle Bin. This can also be referred to as soft-deleted.

To find and restore records in the Recycle Bin:

On the left side of the homepage in CRM, click on the Recycle Bin.
Change the drop down to All Recycle Bin.
Search for the records.
Select the record and click Undelete.

Stage 2 - Emptied from the Recycle Bin or hard-deleted - Data in this stage cannot be recovered from the Recycle Bin but can be accessed via the workbench.

To find and restore records using the Salesforce workbench:

Prior to running the search query, Select Include under Deleted and archived records.

Once the Id for the record is located, choose Undelete from the data drop-down at the top of the page.

Enter the Id and follow the prompts on the screen to restore the record.
Stage 3 - Physically or Permanently deleted - Data in this stage is deleted from the database and only recoverable by contacting Salesforce to request a Data Recovery Service (There is a fee associated with this service).