i purchased CS4 in 2010 and my system crashed and had to install in operating system . I would like to reinstall CS4 . Is that possible?

[Gar1610]

I purchased CS4 a few years ago my system crashed and I had to install new operating system ... can I reinstall it on my computer

[Ned Murphy]

Yes, you should be able to if you have the serial number from the original purchase.  Find your Adobe product serial number quickly

CS4 - http://helpx.adobe.com/creative-suite/kb/cs4-product-downloads.html

You can also download the trial version of the software thru the page linked below and then use your current serial number to activate it.  Be sure to follow the steps outlined in the Note: Very Important Instructions section on the download pages at this site and have cookies enabled in your browser or else the download will not work properly.

CS3 and CS4: http://prodesigntools.com/download-adobe-cs4-and-cs3-free-trials-here.html

What you should do is contact Adobe Support thru chat and ask them to reset your activations.   Do not ask for more than this though or they might not assist you. That way you regain the one that was lost with the crashed machine (you have two available with your license, so you get an extra one back)  You do not have to do this because you should still have the extra one of two,  but it might prove helpful in the future to still have an extra.

For the link below click the Still Need Help? option in the blue area at the bottom and choose the chat option...
Make sure you are logged in to the Adobe site, have cookies enabled, clear your cookie cache.  If it fails to connect try using a different browser.

Serial number and activation chat support (non-CC)
https://helpx.adobe.com/contact.html?step=PHSP-PHXS_downloading-installing-setting-up_licensing-acti...