The front wheel is held on by a fork which in turn is attached to the buggy with a bolt. This bolt can over time tighten itself which can result in your front wheel not turning as expected.
It requires a simple adjustment that can be done with tools most people have in the home, or a local bike shop would be able to help.
Above the front wheel there is a plastic cap. Under this cap there is a nut that holds the front wheel fork onto the stroller. This nut can be loosened slightly (quarter of a turn) to allow the front wheel to swivel more freely. If this is loosened too much, the front wheel can develop a wobble, so this should be loosened in small increments.