10 August 2011
ER-1 is return of goods manufactured and cleared, such sales return will not be reflected in either ER-1 or DSA(RG-1)
for returned goods, you have to intimate the R/O within 24 hours of such receipt at factory, with documents issued by buyer (invoice, where they have reversed the cenvat credit taken), and after verification the R/O will allow you to take credit in RG23A-part 2. goods would be entered in RG-23A part 1
as you have not shared the reason of return, discuss the reason of return with R/O , he will advise you the procedure for next invoicing.