If you have the excel file still with you, then save it as a .xls only. Open Microsft Access> Open > (Choose file format as .xls from the drop down menu in the open dialog). Now check the box which says that first row as heading...and finally save the table and file. Also, make sure that your Lat , Long are decimal degrees (floating point decimal and not the text or string).Bring the table in ArcMap. Right click the table and say display XY data, choose X for Long and Y for Lat. These features should display and then export it as the shapefile...If these XY values are not saved as decimalor double or numeric data type, they wont show up in the display XY features.
If you don't have the xls file , then tr bringing the dbf and try to to display xy data...