Check Customize > Extensions
1. Check if ArcPad Data Manager is in the list, if so, check it
Check Customize > Customize Mode
1. Check ArcPad Data Manger toolbar is in the list, if so, check it
2. If not, select Add From File
3. Navigate to C:\Program Files (x86)\ArcGIS\ArcPad10.2\DesktopTools10.0
4. Select ArcPadToolsGen2.dll
5. Click yes to all the ESRI Assembly Registration Utility questions
If you are having issues with ArcPadToolsGen2.dll you may need to install some prerequisites, for example, the Microsoft Visual Studio 2008 C++ Runtime.