Can I request for a sheriff to accompany me to my ex wife's house for my personal belongings?

Yes. What you are requesting is called a civil standby, and the police can assist you.  If you have been living separately for a very long time, or there is a dispute concerning whether the items belong to you, the answer may be different.  However, in most circumstances, you can obtain a standby to obtain your personal effects post-separation.  Good luck to you.