I messed up ingame chat and information labels.
 

As subject says, is there a simple way to reset those for default settings and positions ?

No. But you can in the future.

After you configure them again exit the game and copy a [ChatWindow] section from your confUser.ini to a separate file.

Then if they are messed up again copy this section from your backup file to confUser.ini.

Not default i think,but it may be better than what you have possibly :

[ChatWindow]
0:-1=-posSize '0.003 0.870 0.206 0.130' -titleStr "Motor Controls" -alpha 130 -ualpha 0 -wrap -history 100
0:262144=-lay 1 -fnt 0 -clr 0
1:-1=-posSize '0.673 0.000 0.326 0.098' -titleStr Voice -alpha 130 -ualpha 0 -wrap -history 40 -timeout 20
1:2=-font 3
2:-1=-posSize '0.003 0.723 0.181 0.145' -titleStr "Secondary Controls" -alpha 130 -ualpha 0 -history 10 -timeout 20
2:6=-font 3
2:5=-font 3
2:4=-font 3
2:7=-font 3
3:-1=-posSize '0.002 0.003 0.531 0.118' -titleStr "Info. Window 1" -border -alpha 130 -ualpha 0 -includeTime -history 100 -timeout 20
3:393216=-fnt 0 -clr 54 -al 2 -tf 1 -sz 1 -sl 1
3:3=-font 3
3:131072=0
3:1=-font 3
4:-1=-posSize '0.171 0.323 0.687 0.352' -titleStr NetStats -title -border -alpha 50 -ualpha 0 -custom
4:-2=-font 3 -color 139 -columnWidth '0.100 0.183 0.322 0.144 0.093 0.081' -columnSort 2

Regards Bp