What do you mean by "3 hydroxy group" ?

In chemistry, and especially in the chemistry of azides which are high energy compounds, it is important to know exactly what you need to accomplish. Otherwise it is hard to suggest/predict what may happen. If you meant a tertiary hydroxyl group, then it may be particularly difficult. I would try DPPA/toluene at 80 degC and hope that the reactivity of your molecule allows for the desired process to occur.

Hi

As Dr. Jacek Martynow mentioned, Diphenyl Phosphorazidate (DPPA) is very useful. Find  in attach a paper on its synthesis and utilities.

Another useful source of information might be: Mukaiyama, Teruaki; Kuroda, Kiichi; Maruyama, Yuji Heterocycles (2010), 80(1), 63-82.

 http://www.organic-chemistry.org/namedreactions/diazotisation.shtm

Hi,

Versatile, and Pure Arenediazonium Tosylates: Their Preparation, Structures, and Synthetic Applicability

V. D. Filimonov, M. Trusova, P. Postnikov, E. A. Krasnokutskaya, Y. M. Lee, H. Y. Hwang, H. Kim, K.-W. Chi, Org. Lett., 2008, 10, 3961-3964.

A Simple and Effective Synthesis of Aryl Azides via Arenediazonium Tosylates

K. V. Kutonova, M. E. Trusova, P. S. Postnikov, V. D. Filimonov, J. Parello, Synthesis, 2013, 45, 2706-2710.

Hi Pallavi

which step did not work? the tosylation or the azadation? what is you rxn conditions? without these information, it's hard to figure the solution. One thing to remind you is to use the anhydrous solvent when you do the tosylation.

Using of anhydrous conditions is very important.