How can we convert ANSI files to UNICODE?
You can convert ANSI files to Unicode format manually, but sometimes this may become very difficult if the PST files are large in size. To convert an ANSI PST file into Unicode format, first create a new Outlook data file in either MS Outlook 2003, 2007 or 2010 and then copy all the emails and other mailbox items from ANSI file to this new Unicode file. This really takes excellent technical knowledge, a lot of hard work and much time (especially when the files are large). I never tried this, I just read about this in an article. You may take help from this article
Other than this, there is one more effective solution for this situation. You can use third-party software to convert an ANSI PST file into Unicode format. There is a software named as SysInfoTools PST Upgrade & Downgrade
that can easily convert ANSI PST to Unicode format and Unicode PST to ANSI format. I recommend you to check its free demo version before buying any other third-party PST converter.