It's either you don't have data left on your account or APN settings is wrong.

Try updating your APN settings by going to Settings > More > Mobile Network > Access Point Names > tap + to add new APN.

Name : Vodafone India
APN : portalnmms
Proxy : 10.10.1.100
Port : 9401
Username : Not Set
Password :  Not Set
Server :  Not Set
MMSC :  http://mms1.live.vodafone.in/mms/
MMS Proxy : 10.10.1.100
MMS Port : 9401
MCC : 404
MNC : 84
Authentication Type : Not Set
APN type : default,supl,mms
APN protocol: Ipv4
Enable/disable APN: APN Enabled
Bearer: Unspecified
MVNO type : None
MVNO Value : Not set

Change MCC and MNC according to your location:

Andhra Pradesh and Telangana : 404 – 13
Assam : 405 – 824
Assam : 405 – 751
Bihar & Jharkhand : 405 – 752
Chennai : 404 – 84
Delhi & NCR : 404 – 11
Gujarat : 405 – 827
Gujarat : 404 – 5
Haryana : 404 – 1
Himachal Pradesh : 405 – 754
Jammu & Kashmir : 405 – 750
Karnataka : 404 – 86
Kerala : 404 – 46
Kolkata : 404 – 30
Madhya Pradesh : 405 – 834
Madhya Pradesh & Chhattisgarh : 405 – 756
Maharashtra & Goa : 404 – 27
Mumbai : 404 – 20
North East : 405 – 755
Orissa : 405 – 753
Rajasthan : 404 – 60
Tamil Nadu : 404 – 43
Uttar Pradesh (East) : 404 – 15
Uttar Pradesh (West) : 405 – 66
Vodafone Punjab : 404 – 88
West Bengal : 405 – 67