I lost the software of Sony ICDP620 and hence could not recognize by the computer and not able to transfer files what should I do now

First of all, here is the main ONLINE SUPPORT page for your model:

http://esupport.sony.com/US/perl/swu-list.pl?mdl=ICDP620&SelectOS=7


And here is a direct link to the ONLINE USER'S MANUAL for that model:

http://www.docs.sony.com/release/ICDP620.pdf


To view the Support Page or the Owner's Manual with Operating Instructions just use your mouse to click on the link, which is the underlined and highlighted text just above. This will open a new web browser page automatically for you and allow you to view the information at the website indicated and the contents of the Owner's Manual.

You may need ADOBE READER installed on your computer to read PDF documents. You can download this free at WWW.ADOBE.COM if necessary. Click on the DOWNLOAD ADOBE READER button on right side of the ADOBE home page when you get there, and then just follow the onscreen instructions to install it.

Here is the driver download page for your product:

http://esupport.sony.com/US/perl/swu-list.pl?mdl=ICDP620

Just select what operating system your computer uses fom the drop down list and then blue highlighted DIGITAL VOICE EDITOR - 1 FILE download link.
Then just follow the onscreen instructions to download and install the software.

Thank you very much and good luck.