Download old version of Photoshop 5.5

if you have the full cs5.5 (not an upgrade from cs2), just install the cs5.5 and skip the cs2 version,

Downloads available:

• Suites and Programs:  CC 2014 | CC | CS6 | CS5.5 | CS5 | CS4 | CS3
• Acrobat:  XI, X | 9,8 | 9 standard
• Premiere Elements:  12 | 11, 10 | 9, 8, 7
• Photoshop Elements:  12 | 11, 10 | 9,8,7
• Lightroom:  5.6| 5 | 4 | 3
• Captivate:  8 | 7 | 6 | 5
• Contribute:  CS5 | CS4, CS3

Download and installation help for Adobe links

Download and installation help for Prodesigntools links are listed on most linked pages.  They are critical; especially steps 1, 2 and 3.  If you click a link that does not have those steps listed, open a second window using the Lightroom 3 link to see those 'Important Instructions'.

It is not likely you will be able to find a download for 5.5, and it is less likely you will be able to install and activate your CS2.  But there is good news.  If you ultimately only want to get CS2 installed and running... see the following...

Error: Activation Server Unavailable | CS2, Acrobat 7, Audition 3 -

http://helpx.adobe.com/x-productkb/policy-pricing/creative-suite-2-activation-end-life.html