Well, this sounds like "I do not have anything but want to know all! How I can do this?"

Particle size: Scherrer equation. There are a few questions already which discussing this. Reliability, assumptions etc. However, if you do not know the phase (lattice parameters, indexing, crystal structure) it likely won't work. And this is a complex field. You first have to determine the translation lattice (lattice parameters) and then you have to find the respective crystal structure. If there is nothing available you need to make some assumptions about the structure type and need to refine the structure. I guess that in fact you don't need the structure since for lattice parameter determination and lattice indexing only the LATTICE is required. On the other hand, if you are not able to confirm the intensities of all reflections it is hard to make sure that you are working with the correct phase.  

u can use highscore plus software.

most of the parameter can be found easily using this sotware.

...and Highscore Plus software is commercial form PANalytical. Then one should perhaps look for alternatives at CCP14.

http://www.ccp14.ac.uk/

PowderCell is non commercial software. It can calculate the coherent scattering area and stressess. About difference between particle size and coherent scattering area yiu know, i think. 

The average particle size can be calculated using Scherrer'sequation. You can find this equation and the method of calculation in many freely available texts.

The particle size calculation can be done using Scherrer'sequation.

The average crystalline size can be determined from XRD spectrum by Scherrer’s equation using softwares such as X’pert and EVA which is the coherent diffracting crystalline domains (crystallite). The average particle size and grain size can be determined from TEM/SEM.

Dear sir

You can calculate Average size of the nanoparticles by using Debye–Scherrer

equation with the help of FWHM (Full Width Half Maxumum) values.

You can follow the attached file it may help you.

Note that for simple Scherrer you do not need any specific software at all. Origin, gnuplot , or similar and a Lorentz or Pseudo-Voigt fitting leads to adequate results (Figure 3 in “synthesis and testing …“).

For the parameters you want to analyse (stresses and lattice paratmers) you need to perform Rietveld refinement from powder diffraction Data (link).

https://www.fkf.mpg.de/4112052/

Article Synthesis and testing of ZnO nanoparticles for photo-initiat...

You can calculate the crystal size directly with the  Scherrer equation for each crystalline peak. The software related to your XRD can calculate crystal size too when you check the different phases. I use a PDXL software related to a Rigaku Diffractometer. 

In addition if  you need the lattice parameters a,b,c you have to consider for each crystallographic plane the value of d spacing.

For a cubic structure a=b=c

d(h,k,l) = a / rad square (h2+k2+l2)

where h, k, l are the Miller index

For a cubic structure you have to select the dspace of the peack with the  maximum

intensity (usually plane 111)

Please use the link given below. May be useful.

http://mahendrakoppolu.blogspot.in/2013/07/online-crystallite-size-calculator.html

Please use the link given below. May be useful.

http://mahendrakoppolu.blogspot.in/2013/07/online-crystallite-size-calculator.html

What u get from XRD is the crystallite size not particle size, unless each particle is single crystal. Small Angle X-Ray Scattering is the technique to determine particle size.

To determine crystallite size I suggest u use the whole pattern (Wiliamson-Hall or more advance Whole Powder Pattern Modeling*) instead of single peak (Scherrer Formula), because there are other information lies beneath the broadening.

U also need to subtratct the instrument broadening (optics) using the standard sample such as SRM 660b (LaB6), 1976b (Al2O3), 640d (si) or CeO2.

Some software with Fundamental Parameter Approach had the advantage to skip the process to determine instrument broadening.

*M. Leoni, T. Confente & P. Scardi, “PM2K: a flexible program implementing Whole Powder Pattern Modelling”, Z. Kristallogr. Suppl. 23 (2006) 249-254.

Xpowder is a very good software to analyse the XRD Pattern 

http://www.xpowder.com/

I think this link can give you some idea sir,

http://www.instanano.com/characterization/theoretical/xrd-size-calculation/