Hi Geraldine and welcome to the Q&A Board,
Sorry to hear about your lost photos. There is a strong possibilty, though not a guarantee, that you can recover the lost images.
Here is an article about photo recovery software that I found to be very effective:
http://www.digicamhelp.com/digital-photo-recovery-and-rescue/There are some free photo resuce programs and one or two are listed here (always read the websites disclaimers before downloading software):
http://www.digicamhelp.com/free-digital-camera-software/index.htmYou can also download free trial versions of photo recovery software that can be purchased. They are usually limited in their functionality, but have enough function so you can get an idea if and how they work.
Also, if I understand you correctly, you deleted a photo from the memory card using your computer. This can cause problems. Here's some information about how memory cards become corrupted and I highly recommend you (and others) read through the list.
http://www.digicamhelp.com/how-memory-cards-become-corrupted/index.htmGood luck recovering you photos. Let us know how it goes.