Found some info on what Latter-day Saints believe
Guardian Angels areBeings in the heavenly realm, especially ancestors, have an interest in man’s doings on earth and are occasionally sent to protect, physically save, comfort, or uphold mortal men. There is no evidence that guardian angels constantly attend every earthly being. The companionship of the Holy Ghost helps one perceive angels sent to comfort an individual. Deceased loved ones occasionally are allowed to visit mortal relatives, and there are many accounts of such happenings in the journals of Latter-day Saints.
Whether or not each individual has a “guardian angel” is a topic addressed some years ago by Elder John A. Widtsoe: Undoubtedly angels often guard us from accidents and harm, from temptation and sin. They may properly be spoken of as guardian angels. Many people have borne and may bear testimony to the guidance and protection that they have received from sources beyond their natural vision. Without the help that we receive from the constant presence of the Holy Spirit, and from possible holy angels, the difficulties of life would be greatly multiplied.
The common belief, however, that every person born into the world has a guardian angel assigned to be with that person constantly, is not supported by available evidence. … An angel may be a guardian angel though he come only as assigned to give us special help. In fact, the constant presence of the Holy Spirit would seem to make such a constant, angelic companionship unnecessary.
So, until further knowledge is obtained, we may say that angels may be sent to guard us according to our need; but we cannot say with certainty that there is a special guardian angel, to be with every person constantly.