What is the procedure/method/t-code for re-open the previous period.  For example: the current period is 02 2007 but some one closed this period and made it to 05 2007, and already so many postings are done.

Answer 1:
To reopen previous period t-code is mmrv, with this you can open previous period only. 

Answer 2:
You can use MMPI ( But SAP never recommends this, it will mess up all stock valuations ) however, using this T-code please go through OSS note 487381, the main contents as  follow:

Before you start period closing with initialization, you must be aware of the consequences of period closing with initialization. This note describes the possible data inconsistencies that might occur if you carry out the initialization in a productive system. The resulting inconsistencies are not to be traced back to a system error but they are a result of the period closing program with initialization

The initialization of the posting period to a previous or to any posting period may lead to the loss of the information of the inventory balances of the previous periods. The book value of the current posting period is taken as the basis also for values of the previous period in this case. If you want to continue working with this new posting period, in addition you should execute report Z_DEL_HIST_ENTRIES attached so that history entries greater or equal to the new posting period will be deleted.

So be careful while opening any periods in MM or FI side.             *-- Bahadur Nath

MM Related:

• Automate the opening of MM periods
• Allow/Disallowed Backposting of Inventory Posting
• Movement Error - Posting Only Possible Between

SAP Material Management Books
SAP MM Books - Certification, Interview Questions and Configuration

SAP Materials Management Tips
SAP MM Configuration Tips and Materials Management Discussion Forum

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