If reports are being displayed without charts there are two things I would suggest looking at…
1. Login and view a report which should contain some charts. Once loaded, view the ~/ApplicationStats.aspx page. It should give you a count of how many reports and charts are in the cache. If there are no charts in the cache then there is a serious problem that needs to be addressed.
2. If the chart cache contains charts (see ~/ApplicationStats.aspx) the other (more probable) thing to check is the actual img link in the html of the rendered reports. Where ever a chart is to be displayed in the report an img tag should appear with its src pointing to the ChartLoader.ashx handler (along with the id of the chart). Open the C1Report xml definition file for all the reports (should be ~/Secure/report.xml). Any report which contains a chart will use the rsubChartViewer sub report to link to the ChartLoader.ashx. What may have happened is the IP address of the web server changed and as a result rsubChartViewer is no longer creates img tags which point to anything (see OnFormat in the rsubChartViewer sub report).
For instance when I was doing work I think it was set to something like Pic.Picture = "http://192.168.1.192/ChartLoader.ashx?report=... however this probably changed when it was moved into production.
3. Another potential reason for charts not being shown is the version of the .net framework installed on the machine. If using .net framework 1.0, please ensure that service pack 3 is installed. The original version appears to contain a bug in the System.Drawing namespace which raises an exception during rendering of charts.