Taskbar apps icons disappeared.

My daughter has an Acer Aspire 5920 series laptop which has Windows 10 O/S. She uses the laptop only about once or twice a week. When opening up the other day she found that the apps icons had disappeared from the taskbar. She assures me she did not knowingly alter anything. I had a look today using Teamviewer ( my daughter lives about 200 miles from me) and saw that , although her apps icons were missing, the system icons were still showing. Also, when I put a curser onto the now "empty" part of the taskbar, a small rectangular shadow appeared which, if clicked, would open one of the apps. In other words, it seems the icons were there but hiding as it were.
I should be obliged if someone could provide a sure fire way of restoring the hidden icons onto the taskbar, bearing in mind I have to work on the pc remotely. I understand I cannot restore Windows 10 to an earlier date as I believe the last system update occurred more than 10 days ago I have checked to make sure my daughter had not, inadvertently, switched off the icons in "settings".