how do I recover deleted pictures from a memory card?

These are pictures that were deleted from the memory card itself? If so, have you done anyhing further such as saving more data to that memory card? The only hope is a recovery service that can extract deleted data from memory devices as long as nothing has been done since the deletion took place.

If the pictures were deleted from the memory card and as long as you have not saved any more pictures to the card you can use a utility like SanDisk Rescue Pro. This handy utility often comes with a free licence when you purchase some SanDisk memory cards.

There are other programs available if you use Google search.

You can use the Recycle Bin to Recover Deleted Pictures on Your Computer to solved the issue about how to recover deleted photos.

1 Open the Recycle Bin (found on your desktop or in the Start Menu) and check there for the deleted picture files.

2 Select the files or folders you want to recover.

3 Right-click and choose "Restore" from the menu. These actions will restore the files to their original location prior to deletion.

Or you can use Photo Recovery to do that.