Do you mean the Helvetica fonts are missing? You need to copy them from your old computer. They are not stored in InDesign.
As Steve wrote, you have to install it from your old computer. But I would strongly recommend to buy new Helvetica as Open Type Font because old fonts have missing new glyphs, T1 have only 255 glyphs (+ space) and all fonts have improved quality since the 80s, OTF would also support the extended OTF capability of InDesign or Illustrator. So you should consider not only to invest in a new hardware but also in fonts. OTF are also compatible between different OS.
Changing styles is easy with the Find Font command.