To access the 'Solver' tool just select 'Excel's 'Tools, Solver...' menu item.
I am assuming here - that you did not notice this. If you did indeed select the 'Tools, Solver...' menu item and no 'Solver Parameters' window appears ...
To verify the 'Solver' tool's existence:
01. Locate and open the 'Microsoft Office 2004' folder (an assumption on my part, since you made no mention of the version of MS Office / Excel you are referring to). Here 'Excel' is version 11.0.
02. Locate and open the 'Office' folder, and then it's 'Add-Ins' folder (... '/Microsoft Office 2004/Office/Add-Ins/').
Do you see the files 'Solver Library' and 'Solver.xla' in the 'Add-Ins' folder? If so, you have the 'Solver' tool installed - even though it is not displayed in the 'Add-Ins' window's list (obtained via 'Excel's 'Tools, 'Add-Ins...' menu item).
If not installed - navigate though the same folders on the 'Microsoft Office 2004' installation CD and drag them over to the hard disk drive based 'Microsoft Office 2004' 'Add-Ins' folder.
I know, the above contradicts what 'Excel's Help, Excel Help' menu item's 'Microsoft Office Help; window displays - when a search for 'Solver tool' is made, and the 'Add-in programs for Microsoft Excel' link (the last one) is selected.
The same applies for the 'Lookup Wizard' and 'Conditional Sum Wizard' 'Add-Ins' items. These features are available via the 'Tools, Wizard, Lookup...' and 'Tools, Wizard, Conditional Sum...' respective sub menu items, and not via the 'Add-Ins' window's list.
To access the 'Report Manager' (also listed as an 'Add-Ins' item) select the 'View, Report Manager...' menu item.