Wrong gcc version linked with nvidia - c++

Question

I had gcc-5 and gcc-7 installed, and when I tried to compile a cuda sample with 'make' i got lot's of errors, after some research i saw that i needed to downgrade my gcc, so i thought the system was using gcc-7 instead of the other and so i uninstalled it using purge, but then gcc was not even recognized, gcc --version gave error. So i purge the other gcc too and installed again with 'sudo apt-get update' and 'suda apt-get install build essential'. 'gcc --version' now already works, but my cuda drivers aren't working anymore. nvidia-smi results in "command not found" and i can't run any cuda sample, although now i can compile it. For example, deviceQuery returns:
cudaGetDeviceCount returned 35
-> CUDA driver version is insufficient for CUDA runtime version
Result = FAIL
'nvcc --version' also works, here's the output:
nvcc: NVIDIA (R) Cuda compiler driver
Copyright (c) 2005-2017 NVIDIA Corporation
Built on Fri_Sep__1_21:08:03_CDT_2017
Cuda compilation tools, release 9.0, V9.0.176
Running 'lshw -numeric -C display' results in:
WARNING: you should run this program as super-user.
*-display
description: 3D controller
product: GM107M [GeForce GTX 950M] [10DE:139A]
vendor: NVIDIA Corporation [10DE]
physical id: 0
bus info: pci#0000:01:00.0
version: a2
width: 64 bits
clock: 33MHz
capabilities: bus_master cap_list rom
configuration: driver=nvidia latency=0
resources: irq:38 memory:f6000000-f6ffffff memory:e0000000-efffffff memory:f0000000-f1ffffff ioport:e000(size=128) memory:f7000000-f707ffff
*-display
description: VGA compatible controller
product: 4th Gen Core Processor Integrated Graphics Controller [8086:416]
vendor: Intel Corporation [8086]
physical id: 2
bus info: pci#0000:00:02.0
version: 06
width: 64 bits
clock: 33MHz
capabilities: vga_controller bus_master cap_list rom
configuration: driver=i915 latency=0
resources: irq:34 memory:f7400000-f77fffff memory:d0000000-dfffffff ioport:f000(size=64) memory:c0000-dffff
WARNING: output may be incomplete or inaccurate, you should run this program as super-user.
I didn't change nothing on my drivers, but reinstalling gcc broke them. How can I solve this?
Thanks
-- EDIT --
When i do 'locate nvidia-smi' i get the following result:
/etc/alternatives/x86_64-linux-gnu_nvidia-smi.1.gz
/usr/bin/nvidia-smi
/usr/share/man/man1/nvidia-smi.1.gz
Although when i go into those directories, like /usr/bin there is no nvidia-smi executable, under /usr/share/man/man1/ there is no nvidia-smi.1.gz
Doing 'cat /proc/driver/nvidia/version' i get:
NVRM version: NVIDIA UNIX x86_64 Kernel Module 384.111 Tue Dec 19 23:51:45 PST 2017
GCC version: gcc version 7.2.0 (Ubuntu 7.2.0-1ubuntu1~16.04)
It still shows the old gcc, i now have gcc-5, not 7

Answer 1

I managed to solve this, actually it was very simple, i just had to reinstall my nvidia drivers by doing:
sudo apt-get purge nvidia*
sudo apt-get update
sudo apt-get install nvidia-384