Check out this FAQ. It contains a function that handles single and multi-select list boxes, combo boxes, ranges, text boxes, option groups, and check boxes. It returns the Where clause without the word Where. It's all based on the Tag property. You only have to do 3 things to make it work.
1. Open a new module and copy the code from the FAQ and paste it into your new module.
2. Define the tag properites of the controls as specified in the FAQ.
3. Open your report like this: DoCmd.OpenReport "ReportName",,,BuildWhere(Me)