You cannot reset an AutoNumber field with the press of a button. However, you can use DAO to program a process that will automate the process I mentioned:
1) Create a new temporary table with an AutoNumber field.
2) Dump the old records to the temp table.
3) Delete the old table.
4) Rename the temp table with the same name as the old table.
Here's some code to get you started:
Dim dbs As DAO.Database
Dim fld As DAO.Field
Dim tdf As DAO.TableDef
Set tdf = dbs.CreateTableDef("TEMP"

Set fld = tdf.CreateField("ID", dbLong)
fld.Attributes = fld.Attributes + dbAutoIncrField
tdf.Fields.Append fld
Set fld = tdf.CreateField("Field1", dbText, 15)
tdf.Fields.Append fld
Set fld = tdf.CreateField("Field2", dbText, 15)
tdf.Fields.Append fld
dbs.TableDefs.Append tdf