Well, it could be a few things, depending on the type of chart.
I'd start by right-clicking the X axis and choosing Format Axis. On the
Scale tab, see if you have "value axis crosses at max category" selected. If
so, uncheck it.
You can also check Chart | Chart Options. Do you have "secondary axis"
listed on the Axes tab?

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> In all of the graphs I have created in PowerPoint, for the first time my
> value axis labels appear on the right side of the graph instead of the
> left.
> How can I fix this?