Sir,

Is there any positively charged nucleophile....

Nucleophile is an species which can either be negative charge or electrically neutral.But in both cases it should carry electron to share i.e acting as an Lewis base.For ex-
1.Neutral nucleophile – like H₂O,NH_3,ROH,RCOOH,RNH_2.R₂NH,RN₃ etc.
2.Negative nucleophile- like Cl^---,Br^---,I-.OH^--CN^--RCOO^--,RO^-- etc.
Nucleophilic substitution reactions are common in organic chemistry.For ex-Hydrolysis of alkyl halide under basic conditions where attacking nucleophile is OH-- and leaving group is halide ion.
R---Br + OH^-- ---------> R-OH + Br^--

Dear student as in the above answer it is explained that nucleophile is an species which is either neutral or negative charge so it means that nucleophiles are not the positive charge species.The related examples are given to you.And no such example exist for positively charge nocleophile.