Did you reset the web server before or after you deactivated/activated the editor features? You should do the IIS reset after you activate the features.
First, go to the form where the editor should be visible. From that page, go to site settings and then site features and then check if the features are active. It is important to be on the form page with the editor, since sometimes the form is in a different site.
Next, check if the following file is present on the server:
\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\CONTROLTEMPLATES\RadEditorList.ascx
If the editor features are activated successfully, the file should be there. If it is not, then the feature was not activated successfully. Check if the account you used to activate the features has administrative privileges. You need to activate the features with an administrator account .
Finally, if you still cannot see the editor, then perhaps there is something wrong with the installation. In this case I suggest that you retract and re-deploy the RadEditor solution and check the steps above.
All the best,
the Telerik team