In the basic version of Dell there should be only 2 unknown devices in Device Manager.

If drivers won’t install automatically you have to install it manually choosing any .inf file from driver directory.

The first one is O2 Micro OZ600xxx Memory Card Reader Driver
PCI\VEN_1217&DEV_8331&SUBSYS_049B1028&REV_05
PCI\VEN_1217&DEV_8331&SUBSYS_049B1028
PCI\VEN_1217&DEV_8331&CC_018000
PCI\VEN_1217&DEV_8331&CC_0180

Download driver for Windows 10 (DRVR_WIN_R300787.EXE – it works on win10):
http://www.dell.com/support/home/us/en/555/Drivers/DriversDetails?driverId=KC9W0&fileid=2731102815
and unpacked version:
http://www.mediafire.com/download/v1hc9ss8kpoafte/O2+Micro+OZ600xxx+Memory+Card+Reader+Driver.zip

The second unknown device is ST Microelectronics Free Fall Sensor:
ACPI\VEN_SMO&DEV_8800
ACPI\SMO8800
*SMO8800

Tested driver on Windows 10 (Chipset_Driver_RCHTX_WN_2.00.10.34_A11.EXE):
http://www.dell.com/support/home/pl/pl/plbsd1/Drivers/DriversDetails?driverId=RCHTX&fileId=3100839469&osCode=WW1&productCode=latitude-e5420&languageCode=PO,EN&categoryId=CS
and extracted driver:
http://www.mediafire.com/download/w9pvzxa4tsfzx6w/STMicroelectronics.zip