Since you have recently installed Raspbian, and current version of Raspbian is STRETCH, I will assume you have installed Raspbian Stretch.
You then installed dump1090-mutability, then installed graphs.
On Stretch, the dump1090-mutability cannot open the DVB-T dongle. Hence no data to feed graphs. You needed following workaround to make dump1090-mutability and graphs work:
sudo wget -O /etc/udev/rules.d/rtl-sdr.rules "https://raw.githubusercontent.com/osmocom/rtl-sdr/master/rtl-sdr.rules"
Since you did not know about above workaround, you removed dump1090-mutability and installed dump1090-fa, which does not need the above workaround.
Things shoul be ok now and graphs should populate, but they did not. Why? Since dump1090-mutability was installed defore graphs were installed, the graphs /collectd configured itself to get data from dump1090-mutability. When you replaced dump1090-mutability by dump1090-fa, the configuration of graphs/collected did not change, so it is still trying to get data from non existant dump1090-mutability.
You need to change the configuration of graphs/collectd to get data from dump1090-fa. This is how to do it:
Modify “collectd.conf” file as follows (Thanks to @GeorgLichtblau for this workaround):
#Open file collectd.conf for editing
sudo nano /etc/collectd/collectd.conf
#Press ctrl+w and type:
#Press Enter key, the cursor will jump to line:
#Add -fa after dump1090 in line starting with URL, as shown below
#Save the file, exit and restart collectd module
sudo systemctl restart collectd
sudo systemctl status collectd
#Create graphs immediately, else you have to wait for a while
sudo adsb-receiver/build/portal/graphs/make-collectd-graphs.sh 24h